Physics Test 60

Result

Physics Test 60

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following is incorrect about the sensitivity of a moving coil galvanometer?

A
It can be increased by increasing the number of turns in the coil.

B
It can be increased by inserting a soft iron cylinder inside the coil.

C
It can be increased by increasing the strength of the magnetic field.

D
It can be increased by using a suspension fibre of a higher restoring couple per unit twist.

Solution

Sensitivity of a moving coil galvanometer is defined as the current i in microampere required to consume 1 millideflection.
∴ Sensitivity

k =θ / i

=NBA / C

Where all the symbols have their usual meaning and C is the torque per unit twist

Thus the sensitivity of the galvanometer can be increased either by increasing the number of turns (N), using strong magnet or increasing the area of the coil .

Hence, the correct option is (D).
Question 2
4 / -1

If the distance between the Earth and the Sun is half its present value, the number of days in a year will be

A
64.5

B
129

C
182.5

D
730

Solution
Question 3
4 / -1

A thin semicircular conducting ring of radius R is falling with its plane vertical in horizontal magnetic induction At the position MNQ, the speed of the ring is V, and the potential difference developed across the ring is

A
Zero

B
1/2 BvπR² and M is at a higher potential

C
πRBv and Q is at a higher potential

D
2RBv and Q is at a higher potential

Solution
Question 4
4 / -1

The van der Waal equation for n moles of a real gas is

(P+a / V²) (V−b) = nRT

Where P is the pressure, V is the volume, T is the absolute temperature, R is the molar gas constant and a,b,c are van der Waal's constants. The dimensions of a :

A
[ML⁸T^-4]

B
[ML⁸T^-2]

C
[ML⁵T^-2]

D
[ML^-1T^-2]

Solution
Question 5
4 / -1

A particle is displaced from a position The work done by the force in an arbitrary unit is

A
8

B
10

C
12

D
16

Solution
Question 6
4 / -1

The ratio of the wavelengths of the longest wavelength lines in Lyman and Balmer series of hydrogen spectrum is

A
3/23

B
5/27

C
7/29

D
9/31

Solution
Question 7
4 / -1

The distance between the sun and the earth is r and the earth takes time T to make one complete revolution around the sun. Assuming the orbit of the earth around the sun to be circular, the mass of the sun will be proportional to

A
r²/ T

B
r²/ T²

C
r³/ T²

D
r³/ T³

Solution
Question 8
4 / -1

Two spherical bodies of masses ′M′ and ′5M′ and radii ′R′ and ′2R′, respectively, are released in free space with initial separation between their centres equal to ′12R′. If they attract each other due to gravitational force only, then what is the distance covered by the smaller body just before collision?

A
1.5R

B
2.5R

C
4.5R

D
97.5R

Solution

Distance between their surfaces

=12R − R − 2R = 9R

Since,

P∝ mass
a∝ mass

We know that,

Distance ∝ acceleration

So, we can write

a₁/a₂=m/5m = s₁/s₂

s₁/s = 51

5s s₁=s₂……(i)

s₁+s₂=9R……(ii)

On solving these equations;

s₁=1.5R

s₂=7.5R

Since smaller ball have more acceleration in same time interval, smaller ball will cover more distance.

Hence, the correct option is (D).
Question 9
4 / -1

The kinetic energies of photoelectrons emitted from a metal are K₁ and K₂ when it is irradiated with lights of wavelengths λ₁ and λ₂, respectively. The work function of the metal is

A
K₁λ₁- K₂λ₂/λ₂- λ₁

B
K₁λ₁+ K₂λ₂/λ₂- λ₁

C
K₁λ₂- K₂λ₁/λ₂- λ₁

D
K₁λ₂+ K₂λ₁/λ₂+ λ₁

Solution
Question 10
4 / -1

A candle of diameter ′d′ is floating on a liquid in a cylindrical container of diameter ′D′ (D>>d) as shown in the figure. If it is burning at the rate of 2 cm/h, the top of the candle will

A
Remain at the same height

B
Fall at the rate of 1cm / h

C
Fall at the rate of 2cm / h

D
Go up at the rate of 1cm / h

Solution