Physics Test

Result

Physics Test - 18

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Weekly Quiz Competition

Question 1
3 / -1

A boatman can row with a speed of 10 kmh^–1. If a river of width 2 km flows at 5 kmh^–1, then what is the direction in which the boatman should row to reach a point on the other bank directly opposite to the point from where he started?

A
Along the flow

B
60° in NW

C
90° to the direction of flow

D
120° to the direction of flow

Solution
Question 2
3 / -1

A rod, 1 m long, made of a material of thermal conductivity 420 W/m/K has one of its ends in melting ice and the other end in boiling water. If its cross-sectional area is 10 cm², then the amount of ice that melts in 1 minute is

A
0.125 g

B
75 g

C
7.5 g

D
450 g

Solution
Question 3
3 / -1

A

B

C

D
none of these

Solution

We can check from options and only option 2 satisfies the given truth table.
Question 4
3 / -1

Two spheres of masses 'm' and 'M' are situated in air and the gravitational force between them is 'F'. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be

A
F/3

B
F/9

C
3 F

D
F

Solution

Gravitational force is independent of the medium, so it will remain the same, i.e. F.
Question 5
3 / -1

In regard to NAND gate the following statements are made.

(1) It is equivalent to an AND gate followed by an inverter.

(2) If all the inputs are low, the output is low.

(3) If all the input is high the output is low.

(4) NAND operation on two elements is equivalent to OR operation on them.

Which of the above statements are correct?

A
1, 2, 3

B
2, 3

C
1,3

D
None of these

Solution

NAND gate is basically AND gate followed by a NOT gate and its truth table is two inputs given below:

Hence only 1 and 3 are true.
Question 6
3 / -1

With two forces acting at a point, the maximum effect is obtained when their resultant is 4N. If they act at right angles, then their resultant is 3N. Then the forces are

A

B

C

D

Solution
Question 7
3 / -1

The required emf of the cell E so as to show null deflection in voltmeter V connected across A and B of the circuit shown in the figure must be [cell and voltmeter are ideal]

A
5.0 V

B
2.5 V

C
7.5 V

D
10.0 V

Solution
Question 8
3 / -1

A particle moves towards east from a point A to a point B at the rate of 4 km/h and then towards north from B to C at rate of 5 km/h. If AB = 12 km and BC = 5 km, then its average speed for its journey from A to C and resultant average velocity direct from A to C respectively are

A

B

C

D

Solution
Question 9
3 / -1

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the

A
crystal structure

B
variation of the number of charge carriers with temperature

C
type of bonding

D
variation of scattering mechanism with temperature

Solution

There are different charge carriers in case of a metal and a semiconductor. Resistance depends upon the number of charge carriers present. So, resistance variation is there due to charge carrier variation.
Question 10
3 / -1

A transistor is operated in common emitter configuration at constant collector voltage Vc = 1.5 V such that a change in the base current from 100 µA to 150 µA produces a change in the collector current from 5 mA to 10 mA. The current gain (b) is

A
67

B
75

C
100

D
50

Solution