Module-1 Light Reflection and Refraction
Lesson 1 : Light Reflection
Conceptual- Based questions and Answers (Light Reflection)
Question 1
What is reflection of light?
Answer
Reflection: When light bounces off a surface and changes direction.
Question-2
What are the two main types of reflections?
Answer
Regular reflection ;Smooth surfaces produce clear, mirror-like reflections.Diffuse reflection:Rough surfaces scatter light in many directions, making them appear non-reflective.
Question -3
Describe the image formed by a plane mirror?
Answer
Virtual, erect,and of the same size as the object.
Question – 4
What is the difference between real image and virtual image?
Answer
Real images are formed by light rays actually converging after reflection.Virtual images are formed by the apparent origin of diverging reflected rays(like in a concave mirror).
Question -5
Can a virtual image be obtained on a screen?
Answer
No. Virtual image cannot be obtained on a screen.
Question-6
How do mirrors work?
Answer
Mirrors use reflection to create virtual images by reflecting light rays.
Question – 7
Explain the formation of a rainbow.
Answer
Formed by the dispersion,refraction and reflection of sunlight in water droplets.
Question – 8
What is lateral inversion?
Answer
It is the phenomenon where left and right are interchanged in a reflected image.
Question – 9
How does the speed of light affect when it passes from air to glass?
Decreases.
Question – 10
Why do rainbows appear?
Answer
Sun’s rays refract and reflect light inside the water droplet, separating into its spatial colors.
Question -11
What is the normal in the context of reflection?
Answer
It is the imaginary line perpendicular to the reflecting surface at the point of incidence.
Question – 12
How is the angle of incidence measured?
Angle between the incident ray and the normal.
Question – 13
What happens to light that is not reflected?
Answer
It can be absorbed by the surface or transmitted through it (If transparent)
Question – 14
Why are some surfaces more reflective than others?
Answer
Smoother surfaces with high electron density reflect light better.
Question 15
Why does a person appear shorter in water than in air?
Answer
Due to the bending of light as it passes from.one medium to another of different optical density.
Question -16
How does reflection change with angle of incidence?
Answer
The angle of reflection changes according to the law of reflection, affecting image position and size.
Question -17
State the conditions for total internal reflections.
Answer
Question -18
Explain the working of a periscope.
Answer
Periscope uses multiple reflections to allow an observer to see objects around obstacles.
Question -19
How do telescopes use mirrors to collect light?
Answer
Large telescopes use concave mirrors to gather and focus faint light from distant objects.
Question -20
What is the law of reflection?
Answer
The angle of incidence (light hitting the surface) is equal to the angle of reflection (light bouncing off)
Question -21
How do different mirror shapes create different images?
Answer
Concave mirrors can focus light to create real or virtual images depending on object distance.
Convex mirrors have wide fields of view but always produce virtual. Diminished images.
Question -22
How are mirrors characterized based on their curvatures?
Answer
Plane mirrors have flat surfaces.While concave and convex mirrors have curved surfaces.
Question -23
What is the focal length of a convex mirror?
Answer
Positive
Question -24
How does the image distance change in a concave mirror when the object is moved from beyond the focus towards the mirror?
Answer
The image distance increases.
Question – 25
Does the color of the surface affect its reflection?
Answer
Colored surfaces absorb specific wavelengths, reflecting only the remaining colors,appearing colored.
Application-Based Questions and Answers (Light reflection)
Question – 26
How is the concept of reflection applied in periscopes?
Answer
Periscopes use multiple reflections to allow users to see over obstacles commonly used in submarines and military applications.
Question -27
Explain how the rear view mirrors in vehicles are designed based on the principle of reflections?
Answer
A rear view mirror is typically convex mirrors to provide a wider field of view reducing blind spots and enhancing safety.
Question – 28
How does the makeup mirror utilize the concept of reflection?
Answer
Makeup mirrors use plane mirrors to show a virtual, upright reflection of the face.
Question -29
Explain the use of concave mirrors in solar furnaces.
Answer
Solar furnaces use concave mirrors to concentrate sunlight onto a focal point creating high temperatures for various industrial applications.
Question -30
Why does water appear shiny when a sign light hits it?
Answer
The water surface acts like a collection of tiny mirrors, reflecting sunlight in various directions, creating a shimmering effect.
Question -31
How is the concept of reflection of light utilized in the design of satellite dishes?
Answer
Parabolic reflectors are used in satellite dishes to focus and collect electromagnetic signals from satellites for communication.
Question -32
How are headlights of vehicles designed to make use of the reflection principle?
Answer
Headlights often use parabolic reflectors to focus and direct light in a specific direction enhancing visibility.
Question -33
Why can we see ourselves in a mirror?
Answer
Light rays bounce off the mirror’s surface and travel back to our eyes forming a virtual image of ourselves.
Question -34
How is the concept of reflection employed in the design of solar water heaters?
Answer
Solar water heaters use reflective surfaces to concentrate sunlight onto a heat absorbing surface, thereby heating water.
Question -35
Describe how a concave mirror is applied in a shaving mirror?
Answer
Concave mirror in a shaving mirror produces a magnified, virtual and erect image, facilitating a closer view for shaving.
Question -36
Describe the application of reflection in the working of microscope.
Answer
A microscope uses concave mirrors to focus light on the slide or specimen, enhancing visibility and magnification.
Question -37
Why do eyeglasses sometimes have anti-reflective coating?
Answer
The coating reduces unwanted reflections on the lens surface, improving image clarity and reducing eye strain.
Question – 38
In what way does the application of reflection pay a role in solar cookers ?
Answer
A solar cooker uses a concave mirror to focus sunlight onto a cooking vessel, increasing the intensity of heat for cooking.
Question – 39
Explain the application of reflection in the functioning of a kaleidoscope.Explain the application of reflection in the functioning of a kaleidoscope.
Answer
A kaleidoscope uses multiple reflections within mirrors to create symmetrical and colorful patterns from small colorful objects inside.
Question – 40
Explain how a dentist’s mirror makes use of reflections.
Answer
A dentist’s mirror uses the principle of reflection to provide a clear view of the patient’s teeth, aiding the dental examinations and procedure.
Numerical-Based Questions and Answers (Concave Mirror)
Lesson- 2 Light Refraction
Conceptual-Based Questions and Answers (Light refraction)
Question -41
What is refraction of light ?
Answer
When light travels from one medium to another(e.g, air to water) it bends due to a change in speed. The bending is called refraction.
Question -42
What is the law of refraction (Snell’s law)?
Answer
When light refracts , the ratio of the sines of angle of incidence to the angle of refraction is equal to the refractive indices of the two media.
Question- 43
What factors affect the amount of bending in refraction?
Answer
Speed of light in each medium,and the angle of incidence.
Question -44
What is the relationship between the speed of light,refractive index and bending?
Answer
The refractive index (n) of a medium is the ratio of speed of light in vacuum to the speed of light in a medium.A higher refractive index indicates a slower speed of light and greater bending.
Question -45
Why does straw appear bent in a glass of water?
Answer
Light bends as it enters the water, causing the straw to appear displaced at the point of refraction.
Question -46
How do lenses work?
Answer
Lenses use refraction to converge or diverge light rays , creating magnified or diminished images.
Question -47
Why is understanding refraction important in various fields?
Answer
Refraction plays a crucial role in optics,designing lenses and prisms, understanding natural phenomena like rainbows, and even in fiber optic communication technology.
Question – 48
How can you differentiate between reflection and refraction?
Answer
Reflection involves bouncing back of light,While refraction involves bending of light as it travels through different media.
Question -49
How does the thickness of a medium affect the amount of bending?
Answer
For a given angle of incidence,thicker mediums generally cause more bending compared to thinner mediums.
Question -50
How does the law of refraction help explain the bending of light?
Answer
By relating the angles and refractive indices, the law explains how light chooses the path that minimizes travel time as it changes mediums.
Question -51
Can you describe real-world examples where refraction affects our daily lives?
Answer
Seeing objects underwater, the twinkling of stars.
Question -52
Why do objects appear shallower underwater?
Answer
Light from the object bends away from the normal as it enters the water making the object appear closer than it actually is.
Question -53
How do prisms work?
Answer
Prisms use refraction to separate white light into its constituent colors(spectrum) due to different wavelengths(colors) bending at slightly different angles.
Question -54
What are the applications of total internal reflection?
Answer
Used in optical fiber for transmitting light with minimal loss and in prisms for reflecting light at specific angles.
Question -55
Why does the sky appear blue?
Answer
Air molecules scatter shorter wavelengths(blue) more than longer wavelengths(red) causing the sky to appear blue.
Application-Based Questions and Answers (Light refraction)
Question -56
Why do submerged sticks appear bent at the water’s surface?
Answer
Refraction bends light entering the denser medium of water, altering its apparent path.
Question -57
How do raindrops create the colourful phenomenon of rainbows?
Answer
Sun’s rays refract and reflect within water drops , dispersing it into its constituent colours due to varying wavelength bending differently.
Question -58
How do eyeglasses correct vision problems ?
Answer
Convex lenses converge light rays, focusing them for farsightedness,and concave lenses diverge rays,pushing them for nearsightedness.
Question -59
How is the principle of refraction applied in the design of eyeglasses to correct vision?
Answer
Eyeglasses use lenses to refract light, to provide clear vision.
Question -60
Explain the concept of refraction is used in the functioning of a magnifying glass.
Answer
A magnifying glass uses converging lenses to bend light and magnify objects for close observation.
Question -61
What makes a prism split into its colour spectrum?
Answer
Refraction causes different wavelengths(colours) of light to bend at different angles, separating them.
Question -62
How do fish see clearly underwater, even though light bends there?
Answer
Fish have adopted lenses in their eyes that adjust the refraction of light , compensating for the bending and allowing them to see clearly.
Numerical-Based Questions and Answers (Convex lens)
NCERT-Based Questions and Solution (Light reflection and refraction)
Module 2 : The Human Eye and the colourful World
Lesson -1 Human eye
Conceptual-Based Questions and Answers (Human eye)
Question -63
Why is the eye considered a sensitive organ?
Answer
It can detect even a small amount of light and perceive a wide range of colours.
Question -64
Discuss the function of the retina in the context of vision.
Answer
Retina contains photo receptors that convert incoming light into electrical signals.These signals sent to the brain for visual reception.
Question -65
Explain the process of accommodation of the human eye.
Answer
It is the ability of the lens to adjust its shape,achieved by contraction and relaxation by the ciliary muscles.
Question -66
Differentiate between the functions of the ciliary muscles and the iris on the eye
Answer
Ciliary muscles control the shape of the lens for accommodation.Iris regulates the size of the pupil, controlling the amount of light entering the eye.
Question -67
Explain how the human eye works as a natural optical device?
Answer
Light enters through cornea and lens focusing it onto the retina.There it is converted into nerve impulses and sent to the brain via optic nerve.
Question -68
Describe the role of cornea and lens in the human eye.
Answer
Cornea bends light initially,Lens adjusts its curvature to focus for clear vision.
Question -69
How does the pupil control the amount of light entering the eye?
Answer
Through the action of Iris.In bright light pupil constricts and in dim light it dilates to allow more light.
Question -70
Discuss the significance of blind spot in the human eye.
Answer
The blind spot is where the optic nerve exits the eye.It is significant because the images falling on this spot are not perceived, but the brain compensates for this gap in vision.
Question -71
Explain the working principle of the human eye as a camera.
Answer
The human eye acts like a camera with a lens (cornea and crystalline lens) , an aperture(pupil) and a photosensitive film (Retina). It captures and processes light to create virtual images.
Question -72
Why is it essential for the lens to change its shape for focusing near and distant objects?
Answer
It is to adjust the focal length ensuring clear vision for objects at various distances.
Application-Based Questions and Answers (Human eye)
Question -73
How do spectacles with convex and concave lenses correct hypermetropia and myopia respectively?
Answer
Convex lenses correct hypermetropia by converging the light before it enters the eye.
Concave lenses correct myopia by diverging light before it reaches the eye.
Question -74
A person complains of blurry vision.Suggest possible eye defects and the corresponding corrective measures.
Answer
Possible defects could be myopia, hypermetropia and Astigmatism. Correction involves concave lenses for myopia, convex lenses for hypermetropia and cylindrical lenses for astigmatism.
Question -75
A person can see nearby objects clearly but has difficulty in focusing on distant objects. What eye defect might they have, and how can it be corrected?
Answer
Myopia (nearsightedness). Corrected by using concave lenses.
Question -76
Explain the role of contact lenses in correcting vision defects?
Answer
Contact lenses directly rests on the eye’s cornea and perform the same corrective function as eyeglasses,providing a more natural field of vision.
Question -77
Discuss the effect of prolonged exposure to screens on eye health.
Answer
Can cause digital eye strain,characterised by symptoms like headache and dry eyes.Take break to reduce strain.
Question -78
Why is it important to have regular eye check-ups, even if one doesn’t have apparent vision problems?
Answer
To detect early signs of eye diseases, ensuring the prevention of vision loss.
Question -79
Discuss the role of the retina in the perception of colours.
Answer
Retina contains three types of colour sensitive cones that respond to different wavelengths, enabling the perception through colour combinations.
Question -80
If a person experiences double vision,what could be the possible causes and how it can be addressed.
Answer
Misalignment of the eyes.Treatment involves corrective lenses, vision therapy or surgery.
Question -81
Discuss the impact of ageing on the human eye and common eye-related issues in older individuals.
Answer
Ageing can lead to presbyopia (loss of accommodation) and increased risk of conditions like cataracts and glaucoma.
Question -82
In what situations would a person need bifocal lenses, and how do they work?
When a person has both near and distant vision problems. They have two parts: one for distance and another for reading.
Lesson -2 Dispersion of white light
Conceptual-Based Questions and Answers (Dispersion of light)
Question -83
What is the essential condition for observing a rainbow?
Answer
The observer must stand with his back towards the sun.
Question -84
Why do clouds appear white?
Answer
Due to the presence of large particles like dust and water droplets scatter light of almost all colors equally.
Question -85
What will be the color of the sky in the absence of atmosphere?
Answer
Appear dark,due to the lack of scattering.
Question -86
Which of blue and red light is deviated more by the prism?
Answer
Blue color is deviated more than the red color, as nR is less than nB
Application-Based Questions and Answers (Dispersion of light)
Question – 87
Module -3 Electricity
Conceptual-Based Questions and Answers
Question -88
Explain why the resistance of a wire increases with its length and decreases with its cross sectional area?
Answer
Resistance of a wire is directly proportional to the length(L) of the wire and inversely proportional to the area of cross section(A).The relationship is described by the formula R = ρL/A
Question -89
Describe the factors that determine the resistance of a given conductor.How does temperature affect the resistance?
Answer
Length (L) : Resistance increases with length.
Cross sectional Area (A) :Decreases with cross sectional area.
Temperature(T): Increases with temperature
Question -90
Explain why the combination of resistances in parallel has a lower equivalent resistance corresponding to the same resistances in series
Answer
In parallel combination multiple paths for current flow reduce the total resistance making the equivalent resistance less than the smallest of individual resistances.This is in contrast to the series circuit
Question -91
Discuss the role of electrons in the flow of electric circuit.How does their motion contribute to electrical conductivity in metals
Answer
Electrons move in response to an electric field, creating a flow of charge.In metals, electrons are the charge carriers, contributing to electrical conductivity.
Question -92
What is the difference between an open circuit and a short circuit? How do they affect the flow of electric current?
Answer
Open circuit : Incomplete circuit ,Preventing current flow.
Short circuit : Low resistance,Causing excessive current flow.
Question -93
Explain why a higher potential difference across a conductor leads to higher current. Use Ohm’s law to support your explanation.
Answer
According to Ohm’s law V = IR , a higher potential difference V leads to higher current(I), provided the resistance(R) remains constant.
Question -94
Discuss the safety measures associated with the use of electrical appliances in homes? Why it is important to follow these guidelines.
Answer
Proper insulation, avoiding overloading, using circuit breakers and following manufacturers guidelines.
Question -95
Discuss the concept of electric power in the context of electrical appliances. How is power related to current and voltage?
Answer
Electric power(P) is the rate at which work is done. P = VI
Application-Based Questions and Answers
Question -96
Discuss the significance of using materials with high conductivity in electrical wires.
Answer
High conductivity ensures that wires have low resistance, minimising energy loss as heat and allowing efficient transfer of electric energy.
Question -97
Explain why it is necessary to earth metallic appliances. How does earth prevent electric shocks in homes?
Answer
Earthing involves connecting metallic appliances to the ground to prevent electric shocks.It provides a low resistance path for current to flow into the ground in case of a fault.
Ncert-Based Questions and solution (Electricity)
Module -4 Magnetic Effects of Electric Current
Conceptual-Based Questions and Answers (Magnetic effect of current)
Question -98
What is the magnetic effect of electric current
Answer
Creation of magnetic field around a conductor when electric current flows through it.
Question -99
Explain the right hand thumb rule with respect to the magnetic field around a current carrying conductor.
Answer
Right hand thumb – direction of current in a straight conductor.
Curling fingers – Direction of the magnetic field lines
Question -100
How does the direction of the magnetic field around a straight current-carrying conductor change with the direction of the current?
Answer
The pattern follows a circular pattern,the field direction is anticlockwise in the case of a vertical current carrying wire when the current flow is from bottom to top and vice-versa.
Question -101
What factors determine the strength of the magnetic field around a current carrying conductor?
Answer
Magnitude of the current and the distance from the conductor
Question -102
How does the shape of a current carrying circular loop affect its magnetic field?
Answer
Produces a magnetic field similar to that of a bar magnet. Shape and orientation of the loop determine the direction of the pattern of the magnetic field lines.
Question -103
Describe the magnetic field pattern around a solenoid carrying current.
Answer
Similar to that of a bar magnet.Magnetic field lines are concentrated inside the solenoid and resemble the field pattern of a bar magnet.
Question -104
Explain the factors influencing the strength of the magnetic field inside a solenoid.
Answer
Number of turns in the coil,Current passing through it and Permeability of the core material.
Question -105
How can you increase the strength of an electromagnet?
Answer
Increasing number of turns in the coil
Increasing the current flowing through it
Using a core material of higher permeability.
Question -106
Describe the behaviour of a magnetic needle when placed near a current carrying conductor
Answer
Align itself perpendicular to the conductor indicating the direction of magnetic field created by the current.
Question
Explain the concept of magnetic field lines and their properties
Answer -107
Imaginary lines used to represent the direction and strength of the magnetic field.Closed and continuous curves.Closer together where the field is stronger and farther apart where the it’s field is weaker.
Question -108
Differentiate between permanent magnet and electromagnet.
Answer
Permanent magnet : Retains its magnetism without the need for an external current.
Electromagnet : Exhibits magnetic property when an electric current flows through it.
Question -109
What is the purpose of a circuit breaker in a domestic electric circuit.
Answer
To protect the circuit and electrical appliances from overload and short circuit by automatically breaking the circuit when excessive current flows through it.
Question -110
Explain the differences between series and parallel circuits. How do they affect the overall resistance and current flow in a circuit?
Solution
| SERIES CIRCUIT |
| Current passing through each resistor is the same. Net effective resistance in the case of series combination is the sum of the individual resistances. Rs = R1+ R2+ R3 The applied voltage is the sum of the potential difference formed across each resistor. The net effective resistance is higher than the highest resistance in the circuit. |
| PARALLEL CIRCUIT |
| Current passing through each resistor is not the same. The reciprocal of the net effective resistance in the case of parallel combination is equal to the sum of the reciprocal of their individual resistances. The potential drop across each resistor is the same. The net effective resistance is lesser than the least resistance in the circuit. |
Question-111
Why is it important to have a grounded (earthed) connection in a domestic electrical system?
Answer
Provides a pathway for excess current to flow safely into the ground,preventing electric shocks and reducing the risk of fire.
Question -112
Describe the function of a fuse in an electrical circuit. How does it differ from a circuit breaker?
Answer
A fuse is designed to melt and break the circuit when the current exceeds a certain limit protecting the circuit from damage.A circuit breaker performs the same function but can be set manually.
Application- Based Questions and Answers (magnetic effects of current)
Question -113
Investigate and list safety measures that should be taken when wiring a new room with electrical outlets and switches.
Answer
Turning off the main power supply,Using proper insulation of wires, grounding the circuit,and ensuring correct wire sizes for the load.
Question -114
Design a simple circuit for a bedroom that includes a light bulb, a switch and an electrical outlet. Explain the wiring connections.
Answer
Connecting the switch in series with the light bulb and connecting the electrical outlet in parallel with the light bulb.
Question-115
A household appliance has a power rating of 1200 watts and operates at 240 volts.Calculate the current flowing through the appliance.
Answer
P = VI I=P/V I = 1200 watts/ 240 volts Ans: 5 Ampere
Question -116
A circuit with multiple devices is connected in parallel.If one device fails, explain how it affects the overall current and voltage in the circuit.
Answer
The voltage across the failed device drops to zero.
Question -117
Discuss the advantages and disadvantages of using LED bulbs compared to incandescent bulbs in domestic lighting.
Answer
LED bulbs ; Energy efficiency, longer lifespan and environmental friendliness.They are more expensive upfront but result in cost savings over time.
INCANDESCENT BULBS: cheaper initially, less energy efficient and have a shorter lifespan.
Module-5 Cbse physics practical for grade 10
Practical 1: Ohm’s law (Link provided below)
Practical 2: Resistors in series (Link provided below)
Practical 3: Resistors in parallel (Link provided below)
Practical 4: Focal length of a convex lens (Link provided below)
Practical 5: Focal length of a concave mirror(Link provided below)
Practical 6: Refraction through a glass slab (Link provided below)
Practical 7:Refraction through a glass prism (Link provided below)
Practical 8:Image formation by a convex lens (Link provided below)
https://edu-physics.com/tag/cbse-class-10-practical