PH | MCQs

Explanation

A moving ball stops due to the action of frictional force.

Friction opposes the motion of the ball, gradually reducing its speed until it comes to a stop.

Explanation

The strength of the magnetic field around a conductor is determined by how much current is flowing.

The magnetic field is directly proportional to the current.

Explanation

Optics is the branch of physics that studies light and its interactions with matter.

It including phenomena such as reflection, refraction, and dispersion.

Explanation

if the phase of vibration Θ = π/ z radians, and you are saying that a quarter of the cycle is completed

Then we can equate these two conditions to find the value of z.

In Simple Harmonic Motion (SHM), one complete cycle corresponds to 2π radians. Therefore, if  Θ = π/ z radian represented a quarter of the cycle, then we can write:

 Θ = π/ z = 1/ 4 x 2 π

simplifying 

  π/ z =  π/ 2

 Now, to find the value of z, we can cross-multiply

z = 2

So, when the phase of vibration Θ = π/ z radians and a quarter of the cycle is completed, the value of z is 2.

Explanation

• An object moving along a circular path is experiencing a change in direction, which means it is constantly accelerating.
• According to Newton's first law of motion, an object in motion will remain in motion with a constant velocity unless acted upon by an external force.
• In the case of an object moving in a circular path, the force of centripetal acceleration is acting on the object, causing it to change direction and accelerate towards the center of the circle.
• Therefore, the object is not in equilibrium.

Explanation

The minute hand of a clock moves 360 degrees (or 2π radians) in 60 minutes, which is equivalent to 1 hour.

To find the angular velocity, we can use the formula:

ω = Δθ / Δt

where ω is the angular velocity, Δθ is the change in angle (2π radians), and Δt is the time (1 hour or 3600 seconds).

Plugging in the values, we get:

ω = 2π radians / 3600 s ≈ 0.00175 rad s⁻¹

So, the angular velocity of the minute hand is approximately 0.00175 rad s⁻¹.

Explanation

According to Newton's 2nd law, the object's acceleration and centripetal force are in the same direction.

Explanation

The EMF induced across the ends of a wire moving through a magnetic field can be calculated using the formula:

E = Blv

Where:

• E is the induced EMF in volts
• B is the magnetic flux density in teslas
• l is the length of the wire in meters
• v is the velocity of the wire in meters per second

Given:

B = 0.10 T

l = 0.20 m

v = 3.0 m/s

Substituting the values into the formula, we get:

E = 0.10 x 0.20 x 3.0

E = 0.06 V

Explanation

Electrons are accelerated by voltages up to 10^9 V in order to find the internal structure of a nucleus.

Explanation

• High-speed electrons from particle detectors are used to determine the diameter of atomic nuclei through techniques such as electron scattering or electron microscopy.
• By measuring the scattering pattern or the diffraction pattern of the electrons, researchers can infer the size and shape of the atomic nucleus, including its diameter.