Physics Test 203

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Physics Test 203

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Weekly Quiz Competition

Question 1
4 / -1

Under what condition angular frequency ω of the damped oscillator would be equivalent to angular velocity Ω of the undamped oscillator.

A
Velocity of oscillator is small

B
Damping constant, b is small

C
Damping constant ,b is large

D
Force applied is small

Solution
Question 2
4 / -1

A point source of light is placed in front of a plane mirror.

A
Only the reflected rays close to the normal meet at a point when produced backward

B
All the reflected rays meet at a point when produced backward

C
Only the reflected rays making a small angle with the mirror, meet at a point when produced backward

D
Light of different colours make different images

Solution

Plane mirror always forms a virtual image of the real object for all the rays emitted by the object. So, when a point source of light is placed in front of a plane mirror, all the reflected rays meet at a point when produced backward.

Option B is correct.
Question 3
4 / -1

A node is a point where there is always

A
Constructive interference

B
Destructive interference

C
Double trough

D
Two crests

Solution

A node is a point along the medium of no displacement. The point is not displaced because destructive interference occurs at this point.
Question 4
4 / -1

Light of wavelength 500 nm is incident on a slit of width 0.1 mm. The width of the central bright line on the screen is 2m. What is the distance of the screen?

A
1 m

B
200 m

C
0.75 m

D
0.5 m

Solution

Beta(central Maxima) = 2 * lambda * D(distance of the screen) / d(distance between slits)

beta = 2 m, wavelength = 500nm = 5 ×10^-7m & d = 0.1mm = 1×10^-4m

► 2 = 2 × 5 × 10^-7 * D/10^-4

► 1 = 5 × 10^-3 D

► D = 1000/5

► D = 200m
Question 5
4 / -1

Sodium has body-centered packing. The distance between the two nearest atoms is 3.7 Å. The lattice parameter is:

A
4.3 Å

B
3.0 Å

C
8.6 Å

D
6.8 Å

Solution
Question 6
4 / -1

The knee voltage of a-n junction diode is 0.8 V and the with of the depletion layer is 2 μm. What is the electric field in the depletion layer?

A
0.4 KV/m

B
0.4 MV/m

C
4 MV/m

D
4 KV/m

Solution

Knee voltage- it is that forward voltage beyond which current start increasing rapidly, but below knee voltage variation of forward current and applied voltage is linear.

The electric field in a region is given by, E=V/l.

where V is the potential and l is the length or distance of the region in which it has to be measured.

now, E=V/l

E=0.8/2×10^-6 m

E= 0.4 MV/m
Question 7
4 / -1

When a pure semiconductor is heated, its resistance:

A
Goes down

B
Goes up

C
Remains the same

D
None of the above

Solution

As temperature increases electrons from the valence band go to the conduction band, so conductivity increases hence resistance decreases.
Question 8
4 / -1

What is the order of forbidden gap in the energy bands of silicon?

A
3.1 eV

B
0.1 eV

C
2.1 eV

D
1.1 eV

Solution

Silicon has a forbidden gap of 1.1 eV at 300 K temperature.
Question 9
4 / -1

Sound waves travel at 350 m/s through a warm air and at 3500 m/s through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from warm air

A
decreases by a factor 10

B
increases by a factor 20

C
increases by a factor 10

D
decreases by a factor 20

Solution
Question 10
4 / -1

In the case of real gases, the equation of state, PV = RT (where P, V and T are respectively the pressure, volume and absolute temperature), is strictly satisfied only if corrections are applied to the measured pressure P and the measured volume V. The corrections for P and V arise respectively due to

A
kinetic energy of molecules and collision of molecules

B
size of molecules and expansion of the container

C
expansion of the container and intermolecular attraction

D
intermolecular attraction and the size of molecules

Solution

According to kinetic theory of gases there is no intermolecular force of attraction between the molecule of gases but its not true as gases liquifise, at high pressure molecular interaction starts due to which pressure on the walls decreases as molecule dragged back so pressure exerted by real gas is less than ideal gas, due to repulsive forces molecule behave as small spheres and hence volume decreases

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Physics Test 203

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Physics Test 203

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Question 1

Velocity of oscillator is small

Damping constant, b is small

Damping constant ,b is large

Force applied is small

Solution

Question 2

Only the reflected rays close to the normal meet at a point when produced backward

All the reflected rays meet at a point when produced backward

Only the reflected rays making a small angle with the mirror, meet at a point when produced backward

Light of different colours make different images

Solution

Question 3

Constructive interference

Destructive interference

Double trough

Two crests

Solution

Question 4

1 m

200 m

0.75 m

0.5 m

Solution

Question 5

4.3 Å

3.0 Å

8.6 Å

6.8 Å

Solution

Question 6

0.4 KV/m

0.4 MV/m

4 MV/m

4 KV/m

Solution

Question 7

Goes down

Goes up

Remains the same

None of the above

Solution

Question 8

3.1 eV

0.1 eV

2.1 eV

1.1 eV

Solution

Question 9

decreases by a factor 10

increases by a factor 20

increases by a factor 10

decreases by a factor 20

Solution

Question 10

kinetic energy of molecules and collision of molecules

size of molecules and expansion of the container

expansion of the container and intermolecular attraction

intermolecular attraction and the size of molecules

Solution

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