Physics Test 285

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Physics Test 285

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Weekly Quiz Competition

Question 1
4 / -1

In a L−C−R series AC circuit, the voltage across each of the component L,C and R is 50V.

The voltage across the L−R combination.

A
50V

B

C
100V

D
0V

Solution
Question 2
4 / -1

Two wires are made up of two different materials with their specific resistances, lengths and areas of the cross-section in the ratio, 2 : 3, 3 : 5 and 4 : 5, respectively.

The ratio of their resistances is given by, __

A
0.5

B
0.25

C
1

D
1.25

Solution

To find the ratio of the resistances of the two wires, we use the formula for resistance:
Question 3
4 / -1

The flux linked with a coil at any instant t is given by ϕ = 10t²− 50t + 250. The induced emf at t = 3s is

A
−190 V

B
−10 V

C
10 V

D
190 V

Solution
Question 4
4 / -1

The distance of Neptune and Saturn from the Sun are nearly 10¹³m and 10¹²m respectively. Ratio of their time period will be

A
10

B
100

C

D
1000

Solution

Among the provided choices, the closest power-of-ten is 10¹= 10, but the exact value is ≈ 31.6. None of the listed options equals 10¹⁰; the value 10¹⁰ is physically impossible. The mathematically correct ratio is ≈ 31.6.
Question 5
4 / -1

Which law a vector quantity must obey?

A
Commutative law of multiplication

B
Triangle law of addition

C
Algebraic law of addition

D
Commutative law of division

Solution
Question 6
4 / -1

According to Hooke's Law, within the elastic limit, which of the following is true?

A
Stress is inversely proportional to strain.

B
Stress is directly proportional to strain.

C
Stress is equal to the modulus of elasticity.

D
Stress is independent of strain.

Solution

Hooke's Law states that for small deformations, stress is directly proportional to the strain.

where k is the proportionality constant and is known as modulus of elasticity.
Question 7
4 / -1

A charged particle moves in a magnetic field B with velocity v. The angle between v and B is θ.

The magnetic force experienced by the particle is proportional to:

A
B only

B
v only

C
sin⁡θ

D
cos⁡θ

Solution

Step 1: Recall the Lorentz magnetic-force formula for a charge q moving with velocity v in a magnetic field B:

F = |q|vBsin⁡θ

Step 2: For a given charge q and given magnitudes v and B, the factor that depends solely on the angle θ between v and B is sin θ.

Step 3: Hence the magnetic force is proportional to sin θ.

Conclusion: Among the listed choices, the correct proportionality is with sin θ.
Question 8
4 / -1

The electric and the magnetic field, associated with an EM wave propagating along the +z-axis, can be represented by

A

B

C

D

Solution
Question 9
4 / -1

What is the required condition, if the light incident on one face of a prism, does not emerge from the other face?

A

B

C

D

Solution
Question 10
4 / -1

The distance between the centres of carbon and oxygen atoms in the carbon monoxide molecule is

Locate the centre of mass of the molecule relative to the carbon atom.

A

B

C

D

Solution