Electric Charges and Fields — Physics STD 12 Science — Question

The colour of the second line of Balmer series is

(a) Blue

(b) Yellow

(c) Red

(d) Violet

The lines of force due to earth’s horizontal magnetic field are:

When the separation between two charges is increased the electric potential energy of the charges.

1. Increases.
2. Decreases.
3. Remains the same.
4. May increase or decrease.

A square loop of side l is moving with a constant velocity v in a uniform magnetic field. The magnitude of induced emf is:

The figure shows a double slit experiment P and Q are the slits. The path lengths PX and QX are nλ and (n+2)λ  respectively, where n is a whole number and λ is the wavelength. Taking the central fringe as zero, what is formed at X

(a) First brigh

(b) First dark

(c) Second bright

(d) Second dark

For a normal eye, the least distance of distinct vision is

(a) 0.25 m

(b)  0.50 m

(c) 25 m

(d)  Infinite

Which of the following statement is false for the properties of electromagnetic waves?

What is the range of the characteristic impedance of a coaxial cable?

A cell of internal resistance 3 ohm and emf 10 volt is connected to a uniform wire of length 500 cm and resistance 3 ohm.  The potential gradient in the wire is

(a) 30 mV/cm

(b) 10 mV/cm

(c) 20 mV/cm

(d) 4 mV/cm

In an electromagnetic wave, the direction of the magnetic induction B is