Physics Test 29

Result

Physics Test 29

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Weekly Quiz Competition

Question 1
4 / -1

Thermal energy of a thermal neutron is order of

A
10⁵ J

B
10^–5 J

C
10^–10 J

D
10^–21 J

Solution

A thermal neutron is free neutron having energy 0.025 eV or 4.0 × 10^–21J.
Question 2
4 / -1

A working transistor with the three legs marked P, Q and R is tested using a multimeter. No conduction is found between P and Q. By connecting the common (negative) terminal of the multimeter to R and the other (positive) terminal to P or Q, some resistance is seen on the multimeter. Which of the following is true for the transistor?

A
It is a pnp transistor with R as emitter.

B
It is an npn transistor with R as collector.

C
It is an npn transistor with R as base.

D
It is a pnp transistor with R as collector.

Solution

From what is given, it is clear that P, Q are collector/emitter (since there is no conduction between them); while R is the base. Hence, Option C is correct.
Question 3
4 / -1

A charged particle moves through a magnetic field perpendicular to its direction. Then

A
both, momentum and kinetic energy of the particle are constant.

B
kinetic energy changes but the momentum is constant.

C
the momentum changes but the kinetic energy is constant.

D
both momentum and kinetic energy of the particle are not constant.

Solution

When a charged particle enters a magnetic field at a direction perpendicular to the direction of motion, the path of the motion is circular. In circular motion the direction of velocity changes at every point (the magnitude remains constant). Therefore, the momentum will change at every point. But kinetic energy will remain constant as it is given by 1/2 mv² and v² is the square of the magnitude of velocity which does not change.
Hence, option C is correct.