Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

What is the equivalent resistance between the points A and B of the network

If a current of 3.0 amperes flowing in the primary coil is reduced to zero in 0.001 second, then the induced e.m.f. in the secondary coil is 15000 volts. The mutual inductance between the two coils is

When we see an object, the image formed on the retina is:

A square of side ‘a’ has charge Q at its centre and charge ‘q’ at one of the corners. The work required to be done in moving the charge ‘q’ from the corner to the diagonally opposite corner is

A luminous object is placed at a distance of 30 cm from the convex lens of focal length 20 cm. On the other side of the lens, at what distance from the lens a convex mirror of radius of curvature 10 cm be placed in order to have an upright image of the object coincident with it

Intensity of magnetic field due to earth at a point inside a hollow steel box is

1. On f but not on u.
2. On u but not on f.
3. On f as well as u.
4. Neither on f nor on u.

When radiation of wavelength   is incident on a metallic surface, the stopping potential is 4.8 volts. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes 1.6 volts. Then the threshold wavelength for the surface is