Physics Test 294

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Physics Test 294

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Weekly Quiz Competition

Question 1
4 / -1

A train of weight 10⁷ N is running on a level track with a uniform speed of 36 km h⁻¹. The frictional force is 0.5 kg f per quintal.

Taking g = 10 ms⁻², the power of the engine is:

A
500 kW

B
50 kW

C
5 kW

D
0.5 kW

Solution
Question 2
4 / -1

The electric potential at a point (x,y) in the x-y plane is given by V = −Kxy

The electric field intensity at a distance r from the origin varies as

A
r²

B
r

C
2r

D
2r²

Solution
Question 3
4 / -1

A dipole of electric dipole moment p is placed in a uniform electric field of strength E.

If θ is the angle between positive directions of p and E, then the potential energy of the electric dipole is largest when θ is:

A
π/4

B
π/2

C
π

D
zero

Solution

The potential energy U of an electric dipole in a uniform electric field is given by:

U = −p⋅ E = −pEcos⁡θ

The potential energy is largest when cos⁡θ is smallest. The smallest value of cos⁡θ is −1, which occurs when θ = π.

Therefore, the potential energy of the electric dipole is largest when θ is:

π

So, the answer is:

π
Question 4
4 / -1

Two slits are separated by a distance of 0.5mm and illuminated with light of wavelength . If the screen is placed at 2.5m from the slits.

The distance of the third bright fringe from the centre will be

A
1.5mm

B
3mm

C
6mm

D
9mm

Solution
Question 5
4 / -1

22g of carbon dioxide at 27^∘C is mixed in a closed container with 16g of oxygen at 37^∘C.

The temperature of the mixture (neglect vibrational degree of freedom)

A
24.2^∘C

B
28.5^∘C

C
32.0^∘C

D
33.5^∘C

Solution
Question 6
4 / -1

2L of water in a container is heated with a coil of 1kW at 27^∘C . The lid of the container is open and energy dissipates at rate of 160Js⁻¹. Find the time after which temperature will rise from 27^∘C to 77^∘C?

[Given specific heat of water is 4.2kJ/kg]

A
8 min 20 sec

B
6 min 2 sec

C
7min

D
14min

Solution
Question 7
4 / -1

A solid, uniform cube of side a and mass M is placed on a fixed, horizontal, perfectly rough surface. A small, point–mass m is fixed to the midpoint of one upper edge of the cube. The cube is now given an infinitesimal push so that it begins to topple about the edge in contact with the ground. Find the minimum coefficient of friction μ_min that will permit the cube to topple completely (i.e. until the adjacent edge touches the ground) without ever slipping on the surface. Assume gravitational acceleration g and ignore air drag. (Take m ≪ M, so the cube’s centre-of-mass remains at its geometric centre.)

A

B

C

D

Solution
Question 8
4 / -1

Spacing between the two slits, d = 0.1 mm

Distance of screen from the slits, D = 1.0 m

Wavelength of light, λ = 5000 Å

Fringe width, β

A
1.0cm

B
1.5cm

C
0.5cm

D
2.0cm

Solution

Step 1: Recall the fringe-width formula for Young’s double-slit experiment:
Question 9
4 / -1

The power used is :-

A
4.5 W

B
6.5 W

C
7.5 W

D
9.5 W

Solution

Step 1: Identify the physical quantity asked.

The phrase “the power used” in a JEE problem, when a constant force is given and the displacement occurs uniformly over the stated time, is interpreted as the instantaneous power P = F⋅v.
Question 10
4 / -1

The time period of oscillation of a simple pendulum of length l is T₁ and the time period of oscillation of a uniform rod of the same length l pivoted at one end and oscillating in a vertical plane is T₂. Amplitude of oscillations in both the cases is small.

A

B
1

C

D

Solution