Physics Test 139

Result

Physics Test 139

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Question 1
4 / -1

A

B

C

D

Solution
Question 2
4 / -1

The amplitude of a damped oscillator decreases to 0.9 times its original magnitude in 5s. In another 10s it will decrease to a times its original magnitude,

A
0.7

B
0.81

C
0.729

D
0.6

Solution
Question 3
4 / -1

A

B

C

D

Solution
Question 4
4 / -1

A, B, C, D, E, F are conducting plates each of area A and any two consecutive plates separated by a distance d. The net energy stored in the system after the switch S is closed is

A

B

C

D

Solution
Question 5
4 / -1

The resistance of the coil of an ammeter is R. The shunt required to increase its range n-fold should have a resistance

A
R/n

B

C

D
nR

Solution
Question 6
4 / -1

A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is

A
+2 D

B
+20 D

C
+5 D

D
Infinity

Solution
Question 7
4 / -1

As the temperature increases, the electrical resistance

A
Increases for both conductors and semiconductors

B
Decreases for both conductors and semiconductors

C
Increases for conductors but decreases for semiconductors

D
Decreases for conductors but increases for semiconductors

Solution

As the temperature increases the resistivity of the conductor increases hence the electrical resistance increases. However, for semiconductor the resistivity decreases with the temperature. Hence electrical resistance of semiconductor decreases.
Question 8
4 / -1

In half wave rectification, if the input frequency is 60 Hz, then the output frequency would be

A
Zero

B
30 Hz

C
60 Hz

D
120 Hz

Solution

In half wave rectifier, the output frequency is same as that of input frequency
Question 9
4 / -1

Given below are two statements

Assertion: Biot-Savart’s law gives us the expression for the magnetic field strength of an infinitesimal current element (Idl) of a current carrying conductor only.

Reason: Biot-Savart’s law is analogous to Coulomb’s inverse square law of charge q, with the former being related to the field produced by a scalar source, Idl while the latter being produced by a vector source, q. In light of above statements choose the most appropriate answer from the options given below

A
Both Assertion and Reason are correct

B
Both Assertion and Reason are incorrect

C
Assertion is correct and Reason is incorrect

D
Assertion is incorrect and Reason is correct

Solution
Question 10
4 / -1

According to scientific investigation, the visible region's highest solar radiation intensity occurs at a wavelength of 480 nm. Calculate the temperature of the surface of sun (Given Wein's constant b = 2.88 × 10-3 m K).

A
4000 K

B
6000 K

C
8000 K

D
106 K

Solution