# Physics (Test 5)

## Tancet Anna University : Mechanical Engineering

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Q.1
Consider an oscillator which has a charged particle and oscillates about its mean position with a frequency of 300 MHz. The wavelength of electromagnetic waves produced by this oscillator is
A. 1 m
B. 10 m
C. 100 m
D. 1000 m
Explaination / Solution: Workspace
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Q.2
The electric and magnetic fields of an electromagnetic wave are
A. in phase and perpendicular to each other
B. out of phase and not perpendicular to each other
C. in phase and not perpendicular to each other
D. out of phase and perpendicular to each other
Explaination / Solution:
No Explaination.

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Q.3
In a series RL circuit, the resistance and inductive reactance are the same. Then the phase difference between the voltage and current in the circuit is
A. π/4
B. π/2
C. π/6
D. zero
Explaination / Solution: Workspace
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Q.4
A thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively. The magnetic induction at the center of the spiral is
A. 5 µT
B. 7 µT
C. 8 µT
D. 10 µT
Explaination / Solution: Workspace
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Q.5
A simple pendulum with charged bob is oscillating with time period T and let θ be the angular displacement. If the uniform magnetic field is switched ON in a direction perpendicular to the plane of oscillation then
A. time period will decrease but θ will remain constant
B. time period remain constant but θ will decrease
C. both T and θ will remain the same
D. both T and θ will decrease
Explaination / Solution:

Hint: Both T θ and decreases as B increases.
Workspace
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Q.6
There is a current of 1.0 A in the circuit shown below. What is the resistance of P ? A. 1.5 Ω
B. 2.5 Ω
C. 3.5 Ω
D. 4.5 Ω
Explaination / Solution: Workspace
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Q.7
Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric flux through each Gaussian surface in increasing order. A. D < C < B < A
B. A < B = C < D
C. C < A = B < D
D. D > C > B > A
Explaination / Solution: Workspace
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Q.8
Two metallic spheres of radii 1 cm and 3 cm are given charges of -1 x 10-2 C and 5 x 10-2 C respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is
A. 3 × 10-2 C
B. 4 × 10-2 C
C. 1 × 10-2 C
D. 2 × 10-2 C
Explaination / Solution: Workspace
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Q.9
A disc of moment of inertia Ia is rotating in a horizontal plane about its symmetry axis with a constant angular speed ω. Another discinitially at rest of moment of inertia Ib is dropped coaxially on to the rotating disc. Then, both the discs rotate with same constant angular speed. The loss of kinetic energy due to friction in this process is,
A. B. C. D. Explaination / Solution:
No Explaination.

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Q.10
The work done by the conservative force for a closed path is
A. always negative
B. zero
C. always positive
D. not defined