Physics Test

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Physics Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

When an electron-positron pair annihilates, how much energy is released?

A
0.8 x 10-13

B
1.6 x 10-13J

C
3.2 x 10^-13 J

D
4.6 x 10-13J

Solution
Question 2
1 / -0

Directions: In the following question, a statement of Assertion is given, followed by a corresponding statement of Reason. Mark the correct answer as:
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.
(c) If Assertion is true, but Reason is false.
(d) If both Assertion and Reason are false.
Assertion : Neutrons penetrate a matter more readily as compared to protons.
Reason : Neutrons are slightly more massive than protons.

A
A

B
B

C
C

D
D

Solution

Here assertion given is correct. The reason given for the assertion is correct but it is not the reason for the assertion.
Question 3
1 / -0

If M0 is the mass of an oxygen isotope 8O17, and Mp and Mn are the masses of a proton and a neutron, respectively, then what is the nuclear binding energy of the isotope

A
(M0- 8M)c2

B
(8Mp+ 9Mn- Mo)c2

C
Moc2

D
(Mo- 17Mn)c2

Solution

Here, Z = 8 and A = 17, therefore,
B.E. = (8M_p+ (17 - 8)M_n- M_o)c²
= (8M_p+ 9M_n- M_o)c²
Question 4
1 / -0

A shell at rest, at the origin explodes into three fragments of masses 1 kg, 2 kg and m kg. The pieces weighing 1 kg and 2 kg fly off with a speed of 5 ms–1along x– axis and 6 ms–1along y– axis respectively. If the 'm' kg piece flies off with a speed of 6.5 ms–1, what must be the total mass of the shell?

A
4 kg

B
5 kg

C
3.5 kg

D
4.5 kg

Solution
Question 5
1 / -0

A nucleus decays by β +emission, followed by γ-emission. If the atomic and mass numbers of the parent nucleus are Z and A, respectively, then the corresponding numbers for the daughter nucleus are

A
Z - 1 and A - 1

B
Z + 1 and A

C
Z - 1 and A

D
Z + 1 and A - 1

Solution

For the positron emission, the mass number decreases by 1 and atomic number remains same. Hence, the corresponding numbers for the daughter nucleus are Z - 1 and A.
Question 6
1 / -0

P and Q are like parallel forces. If P is moved parallel to itself through a distance x, then the resultant of P and Q moves through a distance:

A

B

C

D
None of these

Solution
Question 7
1 / -0

An engine pumps up 100 kg of water through a height of 10 m in 5s. Given that the efficiency of engine is 60%. If g = 10 ms^-2, the power of the engine is :

A
3.3 kW

B
0.33 kW

C
0.033 kW

D
33 kW

Solution
Question 8
1 / -0

During projectile motion, the horizontal velocity

A
first increases then decreases

B
first decreases then increases

C
always increases

D
always constant

Solution
Question 9
1 / -0

A
3 : 1 : 1

B
2 : 3 : 2

C
1 : 2 : 3

D
2 : 3 : 1

Solution
Question 10
1 / -0

In the circuit given below, an A.C. voltage V = 220 volt (r.m.s.) is applied. The maximum voltage across the capacitor will be

A

B

C
220 volts

D
Cannot be determined

Solution

The maximum voltage across the capacitor will be Vmax= Vr.m.s×= 220 ×
Question 11
1 / -0

For a transistor, the current gain α is 0.96. It is used as an amplifier in a common base circuit with a load resistance of 4 kΩ. If the dynamic resistance of the emitter-base junction is 48Ω, then the voltage gain is

A
40

B
80

C
120

D
160

Solution
Question 12
1 / -0

The depletion layer in a p-n junction diode is 10-6m wide and its knee potential is 0.5 V. What is the inner electric field in the depletion region?

A

B

C

D
None of these

Solution

In both forward biasing and reverse biasing, applied potential establishes an internal electric field, which acts against or towards the potential barrier. This internal electric field is weakened or strengthened at the junction. In forward voltage at which the current through the junction starts to increase rapidly, once the applied forward voltage exceeds the knee voltage, the current starts increasing rapidly. In forward biasing condition, the inner electric field is given by:
Question 13
1 / -0

Of the diodes shown in the following diagrams, which one is reverse biased?

A

B

C

D

Solution

A diode is said to be reverse biased if p-type semiconductor of p-n junction is at low potential with respect to n-type semiconductor of p-n junction. It is so for circuit (3).
Question 14
1 / -0

For the given circuit to act as a full-wave rectifier, the AC input should be connected across ..i... and ..ii... and the DC output should appear across ...iii... and ...iv....

i, ii, iii and iv, respectively, are

A
B, D, A and C

B
B, A, C and D

C
C, A, B and D

D
C, D, B and A

Solution

For the given circuit which is acting as a full-wave rectifier, the AC input should be connected across B and D and the DC output should appear across A and C.
Question 15
1 / -0

Two particles start simultaneously from the same point and move along two straight lines, one with uniform velocity and the other from rest with uniform acceleration Let α be the angle between their directions of motion. The relative velocity of the second particle w.r.t. first is least after a time of

A

B

C

D

Solution