Nature and propagation
of light
1. What is the difference between wavefront and wavelet?
|
Wavefront |
Wavelet |
|
The locus of the points at which the particles
of the medium vibrate in the same phase is called the wavefront. |
Every point on the wavefront acts as a source
of disturbance, these disturbances are called wavelets. |
|
The concept of the wavefront is more related to
the propagation of an oscillation in a material media. |
The concept of wavelet is focused on defining
the intrinsic characteristics of oscillation. |
2. What is Huygens’s principle? Does Huygens’s principle apply to sound waves in the air?
Huygens principle is a geometrical construction of a wavelet that is used to determine the position of the wavefront at a later time from its position at any instant.
Yes, It can be applied to sound waves in the air.
3. State Huygens’s
principle? (VVVVI)
It states that each point on a wavefront acts as a source of light so they emit disturbances in all directions with the velocity of light and forward a common tangent drawn at any instant gives a secondary wavefront.
4. If light
travels from one medium to another, does its velocity change? Is it due to a change in frequency?
Yes, the velocity of the wave changes but the frequency remains constant. By the relation, c = f λ we can say that velocity changes due to changes in wavelength.
Types of wavefront- Have a look once
This is enough from this chapter.
Electrical Circuits
1. State
Kirchhoff’s laws. (VVVVI)
2. Why
do we prefer a potentiometer to measure the emf of a cell rather than a voltmeter?
(VVVI)
3. What
is the Wheatstone bridge? Write its principle.
4. What
is Meter Bridge? Write its principle.
5. What
is Potentiometer? Write its principle. (VVVVI)
6. Using a Potentiometer, how can you measure the internal resistance of 2 cells? (VVVI)
7. How
can you compare of emf of 2 cells using a potentiometer? (VVVI)
8. Why
is the ammeter connected in series? (VVVVI)
9. Why
is the voltmeter connected in parallel? (VVVVI)
10. Conversion
of galvanometer into voltmeter.
11. State
joules law of heating. (VVVVI)
Wave Motion
1.
If you are
walking on the moon's surface, can you hear the cracking sound behind you?
There is no atmosphere on the moon's surface because
of its weak gravity. For the propagation of sound waves, a medium is necessary.
This means sound waves cannot propagate through a vacuum. So due to a lack of
medium, the propagation of sound on the moon's surface isn’t possible. So, we cannot
hear the cracking sound behind us.
2.
Distinguish
between progressive wave and standing wave.
|
Progressive wave |
Standing wave |
|
The disturbance travels in the forward direction. |
The disturbances are confined to a particular region. |
|
The amplitude of vibration of each particle is the same. |
The amplitude is zero at nodes and maximum at antinodes. |
3.
State and
explain stationary waves.
Whenever two progressive waves of the same
wavelength and amplitude travel in opposite directions with the same speed in a
medium and undergoes superposition; a resultant wave is formed such wave is
called a stationary wave.
4.
Define
progressive wave. (VVVVI)
A wave that travels from one region of medium to
another region carrying energy is called the progressive wave.
Both transverse and longitudinal waves are
progressive.
5.
Why echo
cannot be heard in a small room?
The minimum distance between the speaker (source)
and the wall (reflector) must be 17m to hear an echo. If a room is small, this
requirement is not fulfilled. Hence, we cannot heat an echo in a small room.
6.
Which
types of waves propagate in liquid, explain?
For the propagation of a transverse wave, the modulus of rigidity of a medium is responsible and for the propagation of the longitudinal wave, the bulk modulus of the elasticity is responsible. A solid has both moduli of rigidity and bulk modulus but a liquid has only bulk modulus. Hence only longitudinal waves can propagate through the liquid.
