Physics Test 289

Result

Physics Test 289

Score
-
out of -
Rank
-
out of -

TIME Taken - -

Weekly Quiz Competition

Question 1
4 / -1

Electrostatic field is -

A
Conservative

B
Non conservative

C
Scalar quantity

D
None of these

Solution

The electrostatic electric field is a conservative field, meaning the work done by it to move a charge between two points is independent of the path taken.

In contrast, electric fields created by a changing magnetic field (induced electric fields) are non-conservative.
Question 2
4 / -1

Which of the following are electromagnetic waves?

A
Cosmic rays

B
Gamma rays

C
β⁺-rays

D
β^--rays

Solution

Key Concept
Electromagnetic (EM) waves are transverse, non-mechanical waves consisting of oscillating electric and magnetic fields that propagate in vacuum with speed

Reject D.

Conclusion
Only gamma rays are electromagnetic waves.
Correct choice: B
Question 3
4 / -1

Charges Q,2Q and 4Q are uniformly distributed in three dielectric solid spheres 1,2 and 3 of radii R/2,R and 2R respectively, as shown in figure. If magnitudes of the electric fields at point P at a distance R from the centre of spheres 1,2 and 3 are E₁, E₂ and E₃ respectively, then

A
E₁> E₂> E₃

B
E₃> E₁> E₂

C
E₂> E₁> E₃

D
E₃> E₂> E₁

Solution
Question 4
4 / -1

A stone exerts a gravitational force on the Earth. Why is the effect of this force not noticeable?

A
The Earth's mass is very large, making the acceleration negligible.

B
The force is canceled by the Earth's reaction force.

C
The stone's force is much higher than other forces acting on the Earth.

D
Newton's third law does not apply to gravitational forces.

Solution

According to Newton's second law (F = ma), the Earth's acceleration due to the stone's gravitational force is extremely small because of the Earth's large mass. Hence, the effect is not noticeable.
Question 5
4 / -1

The Magnus effect explains the lift on a spinning ball due to:

A
Increased pressure on the side with higher air velocity

B
Decreased pressure on the side with higher air velocity

C
Equal pressure on both sides

D
Gravitational potential energy difference

Solution

Bernoulli's equation is given by,

According to Bernoulli's principle, faster-moving air with higher v (on one side of the spinning ball) has lower pressure P compared to the slower-moving air on the opposite side. This pressure difference creates a net upward force (Magnus effect), causing the ball to deviate.
Question 6
4 / -1

The superposition takes place between two waves of frequency f and amplitude a.

Given: Maximum intensity I_max= constant × ____ .

A
a

B
a³

C
a⁴

D
a²

Solution
Question 7
4 / -1

Water enters through end A with speed v₁ and leaves through end B with speed v₂ of a cylindrical tube AB. The tube is always completely filled with water.

Step 1:
In case I, the tube is horizontal and in case II, it is vertical with end A upwards and in case III, it is vertical with end B upwards.

We have v₁= v₂ for

A
case I

B
case II

C
case III

D
each case

Solution

The continuity equation for fluid flow states that the mass flow rate must remain constant throughout the tube. Since the tube is always completely filled with water and water is incompressible, the volume flow rate must also remain constant. This implies:

Av₁= Av₂

where A is the cross-sectional area of the tube, v₁ is the speed of water entering at end A, and v₂ is the speed of water leaving at end B. Since A is constant, we have:

v₁= v₂

This holds true for all cases (horizontal, vertical with end A upwards, and vertical with end B upwards).

Answer: each case
Question 8
4 / -1

A time dependent force F = 3t²+ 6t acts on a particle of mass 18kg. If particle starts from rest, the work done by the force during the first 3 second, will be:

A
40.5 J

B
324 J

C
81 J

D
262 J

Solution

To Find:
Work done by the force during the first 3 seconds

Solution:
To find the work done by the force during the first 3 seconds, we can use the work-energy theorem. The work done by the force is equal to the change in kinetic energy of the particle.
Question 9
4 / -1

If λ_v, λ_x and λ_m represent the wavelengths of visible light, X-rays and microwaves respectively, then:

A
λ_m> λ_x> λ_v

B
λ_v > λ_m > λ_x

C
λ_m> λ_v> λ_x

D
λ_v > λ_x > λ_m
Solution
Step 1: Recall the order of the electromagnetic spectrum.

The electromagnetic spectrum arranges different types of radiation by wavelength. The general order from longest to shortest wavelength is: Radio waves > Microwaves > Infrared > Visible light > Ultraviolet > X-rays > Gamma rays.

Step 2: Identify the relative positions of the given radiations.

Based on the spectrum, we can place the given radiations in order of decreasing wavelength:
- Microwaves (λ_m)
- Visible light (λ_v)
- X-rays (λ_x)
Step 3: Formulate the inequality.

Since microwaves have a longer wavelength than visible light, and visible light has a longer wavelength than X-rays, we can write the following relationship:
Question 10
4 / -1

A rectangular plate is measured as follows:
Length L = (12.0 ± 0.2)cm
Width W = (3.0 ± 0.1)cm
Using error propagation for multiplication, report the area A with its uncertainty and correct significant figures.

A
A = (36 ± 2)cm²

B
A = (36.0 ± 1.8)cm²

C
A = (36.0 ± 0.9)cm²

D
A = (36 ± 1)cm²

Solution