Electric Charges and Fields — Physics STD 12 Science — Question

A metallic block carrying current I is subjected to a uniform magnetic induction  as shown in the figure. The moving charges experience a force  given by ........... which results in the lowering of the potential of the face ........ Assume the speed of the carriers to be v

(a) eVB, ABCD

(b) eVB, EFGH

(c) -eVB, ABCD

(d) -eVB, EFGH

The period of oscillations of a magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be

(a) 1.0 sec

(b) 0.5 sec

(c) 0.25 sec

(d) 2.0 sec

The electric field lines are far apart where electric field is:

27 small drops of water with equal radius and equal charge comprised to form one big drop. The ratio of capacitance of a big drop and capacitance of a small drop will be:

Consider the situation shown in figure. The straight wire is fixed but the loop can move under magnetic force. The loop will:

The impurity atom added to germanium to make it N-type semiconductor is

(a) Arsenic

(b) Iridium

(c) Aluminium

(d) Iodine

Mark out the correct options.

1. The energy of any small part of a string remains constant in a travelling wave.
2. The energy of any small part of a string remains constant in a standing wave. 
3. The energies of all the small parts of equal length are equal in a travelling wave.
4. The energies of all the small parts of equal length are equal in a standing wave.

The de-Broglie wavelength associated with the particle of mass m moving with velocity v is

(a) h/mv

(b) mv/h

(c) mh/v

(d) m/hv