Electric Charges and Fields — Physics STD 12 Science — Question

Mark the correct options.

1. The luminous efficiency of a monochromatic source is always greater than that of a white light source of same power.
2. The luminous efficiency of a monochromatic source of wavelength 555nm is always greater than that of a white light source of same power.
3. The illuminating power of a monochromatic source of wavelength 555nm is always greater than that of a white light source of same power.
4. The illuminating power of a monochromatic source is always greater than that of a white light source of same power.

What is the magnetic field at point O due to current carrying wires shown in figure?

What will be the difference in the chemical properties of radioactive isotopes and stable isotopes of an element?

Answer the following questions:
The charged currents in the outer conducting regions of the earth’s core are thought to be responsible for earth’s magnetism. What might be the ‘battery’ (i.e., the source of energy) to sustain these currents?

When a current is established in a wire, the free electrons drift in the direction opposite to the current. Does the number of free electrons in the wire continuously decrease?

If the speed of a rod moving at a relativistic speed parallel to its length is doubled,

1. The length will become half of the original value.
2. Mass will become double of the original value.
3. The length will decrease.
4. The mass will increase.

A source emits 45 joules of energy in 15s. What is the radiant flux of the source?

Write the unit of capacitance and its dimensional formula.

Under what condition the force acting on a charge moving through a uniform magnetic field is minimum?