Electric Charges and Fields — Physics STD 12 Science — Question

A nucleus decays by  emission followed by a gamma emission. If the atomic and mass numbers of the parent nucleus are Z and A respectively, the corresponding numbers for the daughter nucleus are respectively.

(a) Z  - 1 and A - 1

(b) Z + 1 and A

(c) Z - 1  and A

(d) Z + 1 and A - 1

An inductor, L a resistance R and two identical bulbs, and    are connected to a battery through a switch S as shown in the figure. The resistance R is the same as that of the coil that makes L. Which of the following statements gives the correct description of the happenings when the switch S is closed

(a) The bulb B2 lights up earlier than B1 and finally both the bulbs shine equally bright

(b) B1 light up earlier and finally both the bulbs acquire equal brightness

(c) B2 lights up earlier and finally B1 shines brighter than B2

(d) B1 and B2 light up together with equal brightness all the time

Two magnets of equal mass are joined at right angles to each other as shown the magnet 1 has a magnetic moment 3 times that of magnet 2. This arrangement is pivoted so that it is free to rotate in the horizontal plane. In equilibrium what angle will the magnet 1 subtend with the magnetic meridian

(a)

(b)

(c)

(d)  0°

Assertio : Hydrogen atom consists of only one electron but its emission spectrum has many lines.  

Reason  : Only Lyman series is found in the absorption spectrum of hydrogen atom whereas in the emission spectrum, all the series are found.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

If an electric dipole is placed in an electric field, then the value of the torque acting on it will be:

An object is placed 12 cm to the left of a converging lens of focal length 8 cm. Another converging lens of 6 cm focal length is placed at a distance of 30 cm to the right of the first lens.  The second lens will produce

(a) No image	(b) A virtual enlarged image
(c) A real enlarged image	(d) A real smaller image

The material suitable for making electromagnets should have:

The following truth table is for: ABY 110 101 011 001

In a stationary wave,

1. All the particles of the medium vibrate in phase.
2. All the antinodes vibrate in phase.
3. The alternate antinodes vibrate in phase.
4. All the particles between consecutive nodes vibrate in phase.

In a nuclear reaction some mass converts into energy. In this reaction total B.E of reactants when compared with that of products is: