Physics Test

Result

Physics Test - 1

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
4 / -1

If a person travels from the equator to the poles, he finds that the value of acceleration due to gravity (g) ____

A
Decreases

B
Increases

C
Remains constant

D
Decrease upto a certain latitude, becomes zero and then it increases

Solution

If a person travels from the equator to the poles, he finds that the value of acceleration due to gravity (g) increases.

Value of effective g increases as we move from equator to north pole because on equator its value is less due to earth's rotational motion and consequent centrifugal force. Moreover, the equator of the earth is at a larger distance from the centre of the earth as compared to the poles. This is another reason why g is greater on the pole than the equator.
Question 2
4 / -1

At temperature T = 300 K, an n-type silicon contains donor concentration, N_D = 10¹⁴ cm^–3 and intrinsic carrier concentration ղ_i = 1.5 × 10^–10 cm^–3. Assume minority carrier lifetime of holes is τ_po = 10 μsec. Then lifetime of majority carrier electron is _____.

A
444.4 Sec

B
44.44 Sec

C
52.55 Sec

D
525.5 Sec

Solution

Majority carrier lifetime in n-type semiconductor is given by:
Question 3
4 / -1

A bullet of mass 20 g has an initial speed of 1 ms⁻¹, just before it starts penetrating a mud wall of thickness 20 cm. If the wall offers a mean resistance of 2.5 × 10⁻² N, the speed of the bullet after emerging from the other side of the wall is close to:

A
0.3 ms^-1

B
0.4 ms^-1

C
0.1 ms^-1

D
0.7 ms^-1

Solution
Question 4
4 / -1

A tube of length L is filled completely with an incompressible liquid of mass M and closed at both the ends. The tube is then rotated in horizontal plane about one of its ends with a uniform angular velocity ω. The force exerted by the liquid at the other end is:

A

B

C

D

Solution

The force exerted by liquid at the other end is the centripetal force due to rotation. The case can be treated as rotation of the center of mass of the liquid at distance L/2 from the axis of rotation.
Question 5
4 / -1

Ratio of rms velocities of O₂ and H₂ at equal temperature will be?

A
1 : 4

B
1 : 1

C
4 : 1

D
2 1

Solution
Question 6
4 / -1

The electromagnetic waves travel with a velocity:

A
Equal to the velocity of sound

B
Equal to the velocity of light

C
Less than the velocity of light

D
None of these

Solution

Electromagnetic Waves: A changing electric field produces a changing magnetic field and vice versa, giving rise to a transverse wave known as an electromagnetic wave.

The time-varying electric and magnetic fields are mutually perpendicular to each other and also perpendicular to the direction of propagation of this wave.

Maxwell found that the speed of the electromagnetic wave depends on the permeability and permittivity of the medium through which it travels. The speed of an electromagnetic wave in free space is given by,
Question 7
4 / -1

Light can travel in vacuum and sound waves cannot because ________.

A
speed of sound is very slow than light

B
light waves are electromagnetic in nature

C
sound waves are electromagnetic in nature

D
None of these

Solution

Light can travel in a vacuum because the light is electromagnetic in nature which requires no medium as electric fields and magnetic fields constantly generate each other as the wave propagates.

Sound waves require a medium to travel. The speed of sound is faster in solid materials, slower in liquids and slowest in gases.

The speed of light in a vacuum is commonly given the symbol c. It is a universal constant that has the value c = 3 x 10⁸ m/second.
Question 8
4 / -1

An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, then:

A
The effective base width increases and common – emitter current gain increases

B
The effective base width increases and common – emitter current gain decreases

C
The effective base width decreases and common – emitter current gain increases

D
The effective base width decreases and common – emitter current gain decreases

Solution

An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, then effective base width decreases and common – emitter current gain increases.

If the reverse bias voltage across the base collector junction is increased, then their effective base width will decrease and collector current will increase, therefore their common-emitter current gain increases.
Question 9
4 / -1

A magnet of dipole moment 2Am² is deflected through 30^∘from magnetic meridian. The required deflecting torque is

A

B

C

D
None of these

Solution
Question 10
4 / -1

The electromagnetic waves can be produced by:

A
A charge particle at rest

B
A charge particle moving with a constant velocity

C
A charge particle moving with constant acceleration

D
A charge particle can’t produce electromagnetic waves
Solution
The property of matter which is responsible for electromagnetic phenomenon is called charge. The space or region around the current carrying wire/moving electric charge or around the magnetic material in which force of magnetism can be experienced by other magnetic material is called as magnetic field/magnetic induction by that material/current. The space or region around the electric charge in which electrostatic force can be experienced by other charge particle is called as electric field by that electric charge.
- When a charge particle is at rest then it only creates electric field around it.
- When a charge particle is moving with a constant velocity then it equivalent to an electric current which only creates a magnetic field around it.
- When a charge particle is moving with an acceleration then it produced an electromagnetic wave around it.