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