Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions

A milli voltmeter of 25 milli volt range is to be converted into an ammeter of 25 ampere range. The value (in ohm) of necessary shunt will be ______.

Assertion: The poles of magnet can not be separated by breaking into two pieces.

Reason: The magnetic moment will be reduced to half when a magnet is broken into two equal pieces.

A magnetic dipole is acted upon by two magnetic fields which are inclined to each other at an angle of 75°. One of the fields has a magnitude of 15 mT. The dipole attains stable equilibrium at an angle of 30° with this field. The magntidue of the other field (in mT) is close to ______.

A magnetic dipole is under the influence of two magnetic fields The angle between the field directions is 60° and one of the fields has a magnitude of 1.2 × 10^–2 T. If the dipole comes to stable equilibrium at an angle of 15° with this field, what is the magnitude of other field?

A very small magnet is placed in the magnetic meridian with its south pole pointing north. The null point is obtained 20 cm away from the centre of the magnet. If the earth¢s magnetic field (horizontal component) at this point be 0.3 gauss, the magnetic moment of the magnet is ______.

A cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by ______.

If n cells each of emf e and internal resistance r are connected in parallel, then the total emf and internal resistance will be ______.

The nature of parallel and anti-parallel currents are ______.

Let the magnetic field on earth be modelled by that of a point magnetic dipole at the centre of earth. The angle of dip at a point on the geographical equator is ______.

Which of the following is correct about magnetic monopole?

Which of the following graphs represents the correct variation of inductive reactance X_L with frequency u?

In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be ______.

Which of the following graphs represents the correct variation of capacitive reactance X_c with frequency v u?

A straight line plot showing the terminal potential difference (V) of a cell as a function of current (I) drawn from it, is shown in the figure. The internal resistance of the cell would be then ______.