Ray and beam - class-VII
Quiz covering the properties and behavior of light rays and beams, including definitions, types (convergent, divergent, parallel), light sources, and optical phenomena such as refraction and shadow formation for Class VII students.
Questions
Which of the following is correct for the beam which enters the medium ?
- Travel as a cylindrical beam
- Diverge
- Converge
- Diverge near the axis and converge near the periphery
The speed at which the light travels in vacuum is.
- $3 \times 10^{6} m/s $
- $3 \times 10^{8} m/s $
- $3 \times 10^{10} m/s $
- $3 \times 10^{12} m/s $
If a parallel beam of light having intensity I is incident normally on a perfectly reflecting surface, the force exerted on the surface, equal F. When the surface is held at an angle $ \theta $ the force is
- $ 2F tan \theta $
- $ F cos \theta $
- $ F cos^2 \theta $
- $ 2 F $
The shape of spot light produced when bright sunshine passes perpendicular through a hole of very small size, is:
- Square because hole is square
- Round because it is an image of the sun
- Round with a small pinumbra around it
- Square with a small pinumbra
A light is said to be divergent when :
- all the rays travel parallel to each other
- all the rays spread from a point source of light
- all the rays converge together to a single point
- it travels in an irregular pattern
A light is said to be convergent when :
- all the rays travel parallel to each other
- all the rays spread form a point source of light
- all the rays converge towards a single point
- it travels in an irregular pattern
A narrow stream of light is called as :
- Ray
- Beam
- Sunlight
- None of these
A broad stream of light is called a :
- Ray
- Beam
- Twilight
- Sunlight
- True
- False
A beam of light is made up of:
- Rays
- Droplets
- Clusters
- Groups
- True
- False
Which of the following is the sources of light?
- Lamp
- Tube light
- CFL
- All of the above
Which of the following is true about observation of light?
- When we switch on the torch we can observe the beam of light
- Sun light can be observed in early morning when sun rises
- We can observed beam of light of sun through a hole
- All of the above
Which of the following is not the sources of light?
- Candle
- Black body
- Sun
- Bulb
In which of the following natural light can be observed?
- Tube light
- Bulb
- Sun
- Moon
Physical processes are sometimes described visually by lines. Only the following can cross.
- Streamlines in fluid flow
- Lines of forces in electrostatics
- Rays in geometrical options
- Lines of force in magnesium
A glass slab is placed in the path of convergent light.. The point of convergence of light .......... .
- moves away from the slab
- moves towards the slab
- remains at the some point
- undergoes a lateral shift
A beam of light passes through layers of following different substances each 10 cm thick normally. In which substance does the beam take more to pass through?
- Glass slab $(\mu =1.5)$
- water $(\mu =1.33)$
- Fibre slab $(\mu =1.65)$
- Alcohol slab $(\mu =1.36)$
Sun rays on the surface of the earth
- form convergent beam
- form divergent beam
- form parallel beam
- None of these
A wave $ y = 10 sin (ax + bt) $ is reflected fron a dense medium at an origin. if 81% of energy is reflected thn the equation of reflected wave is :
- y= sin -8.1 sin (ax - bt)
- y= sin 8.1 sin (ax - bt)
- y= sin -9 sin (ax - bt)
- y= sin 10 sin (ax - bt)
If the angle of elevation of sun increases from ${0}^{o}$ to ${90}^{o}$ then what will be the change in length of shadow of tower?
- No change in length of shadow
- Length of shadow increases
- Length of shadow decreases
- Length of shadow will be zero
In a room lighted by an electric bulb, it is found that the shadow of the ceiling fan hung in the centre is falling on a wall opposite to the door. What can you say about the position of the bulb?
- On the wall having the door
- On the wall facing the door
- On the wall on your right as you enter the room
- On the wall on your left as you enter the room
Which of the following statement is true?
- All light is electromagnetic wave
- Electromagnetic energy is created only by heat
- Matter emits a single, unique photon when it is heated
- All of these