A paisa coin is made up of AI-Mg alloys and weighs 0.75 g. It has a square shape and its diagonal measures 17 mm. It is electrically neutral and contains equal amount of positive and negative charges. Treating the paisa coins made up of only AI, find the magnitude of equal number of positive and negative charges. What conclusion do you draw from this magnitude?

A and B have identical size and same mass. A becomes A²⁺ and B become B^2- . Will A²⁺ and B^2- still have the same mass? Why?

Two charges 2 \(\mu \)C and -2\(\mu \) C  are placed at points A and B, 6 cm apart. What is the direction of the electric field at every point on this surface?

First a set of n equal resistors of R each are connected in series to a battery of emf E and internal resistance R and current I is observed to flow. Then, the resistors are connected in parallel to the same battery. It is observed that the current is increased 10 times. What is n?

A short bar magnet has a magnetic moment of 0.48 J/T. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of 10cm from the centre of the magnet on
(i)  the axis,
(ii) the equatorial lines (normal bisector) of the magnet.

Consider the plane S formed by the dipole axis and the axis of the earth. Let P be point on the magnetic equator in S. Let Q be the point of intersection of the geographical and magnetic equators. Obtain the declination and dip angles at P and Q.

Why is the coil of dead beat galvanometer wound on a metal frame?

What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?

A Cassegrain telescope uses two mirrors as shown in the figure. Such a telescope is built with the mirrors 20mm apart. If the radius of curvature of large mirror is 220mm and the small mirror is 140 mm, where will the final image of an object at infinity be?

In normal case, emitter-base junction is the forward bias and collector-base junction is reverse biased. What will happen if emitter is reverse biased and collector is forward biased?