Nuclei — Physics STD 12 Science — Question

Two identical batteries, each of e.m.f. 2 volt and internal resistance 1.0 ohm are available to produce heat in an external resistance R = 0.5 ohm by passing a current through it. The maximum Joulean power that can be developed across R using these batteries is

(a) 1.28 watt

(b) 2.0 watt

(c)  watt

(d) 3.2 watt

In one average-life:

1. Half the active nuclei decay.
2. Less than half the active nuclei decay.
3. More than half the active nuclei decay.
4. All the nuclei decay.

Assertion :   Through the same current flows through the line wires and the filament of the bulb but heat produced in the filament is much higher then that in line wires.

Reason     : The filament of bulbs is made of a material of high resistance and high melting point.

(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 reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Following is the relation between current and charge   then value of V_L will be

(a)

(b)

(c)

(d)

Heat and work are equivalent. This means:

1. When we supply heat to a body we do work on it.
2. When we do work on a body we supply heat to it.
3. The temperature of a body can be increased by doing work on it.
4. A body kept at rest may be set into motion along a line by supplying heat to it.

Of the following pairs of species which one will have the same electronic configuration for both members?

The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photocurrent is recorded. An electric field is switched on which has a vertically downward direction.

1. The photocurrent will increase.
2. The kinetic energy of the electrons will increase.
3. The stopping potential will decrease.
4. The threshold wavelength will increase.

When current is passed in antimony-bismuth couple, then

(a) The junction becomes hot when the current is from bismuth to antimony

(b) The junction becomes hot when current flows from antimony to bismuth

(c) Both junctions become hot

(d) Both junctions become cold

Due to 10 ampere of current flowing in a circular coil of 10 cm radius, the magnetic field produced at its centre is 3.34 . The number of turns in the coil will be

(a) 5000

(b) 100

(c) 50

(d) 25