An ionization chamber with parallel conducting plates as anode and cathode has 5 
electrons and the same number of singly-charged positive ions per 
. The electrons are moving at 0.4 m/s. The current density from anode to cathode is 
. The velocity of positive ions moving towards cathode is
|
(a) 0.4 m/s |
(b) 16 m/s |
(c) Zero |
(d) 0.1 m/s |
(d) 0.1 m/s
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Magnetic field due to a ring having n turns at a distance x on its axis is proportional to (if r = radius of ring)
|
(a) |
(b) |
(c) |
(d) |
An electric bulb marked 40 W and 200 V, is used in a circuit of supply voltage 100 V. Now its power is
|
(a) 100W |
(b) 40W |
(c) 20W |
(d) 10W |
Magnetic field intensity is defined as
|
(a) Magnetic moment per unit volume |
|
(b) Magnetic induction force acting on a unit magnetic pole |
|
(c) Number of lines of force crossing per unit area |
|
(d) Number of lines of force crossing per unit volume |
At a certain place the horizontal component of the earth’s magnetic field is B0 and the angle of dip is 45o. The total intensity of the field at that place will be
|
(a) B0 |
(b) |
(c) 2B0 |
(d) |
An infinitely long conductor PQR is bent to form a right angle as shown. A current I flows through PQR The magnetic field due to this current at the point M is H1. Now another infinitely long straight conductor QS is connected at Q so that the current is I/2 in QR as well as in QS, The current in PQ remaining unchanged. The magnetic field at M is now 
The ratio 
is given by
|
(a) |
(b) 1 |
(c) |
(d) 2 |
A polariser is used to
|
(a) Reduce intensity of light |
(b) Produce polarised light |
|
(c) Increase intensity of light |
(d) Produce unpolarised light |
Two identical parallel plate capacitors are connected in series to a battery of 100 V. A dielectric slab of dielectric constant 4.0 is inserted between the plates of second capacitor. The potential difference across the capacitors will now be respectively
|
(a) 50 V, 50 V |
(b) 80 V, 20 V |
(c) 20 V, 80 V |
(d) 75 V, 25 V |
A piece of fuse wire melts when a current of 15 ampere flows through it. With this current, if it dissipates 22.5 W, the resistance of fuse wire will be
|
(a) Zero |
(b) 10 Ω |
(c) 1 Ω |
(d) 0.10 Ω |
A step-down transformer is connected to 2400 volts line and 80 amperes of current is found to flow in output load. The ratio of the turns in primary and secondary coil is 20 : 1. If transformer efficiency is 100%, then the current flowing in primary coil will be
|
(a) 1600 A |
(b) 20 A |
(c) 4 A |
(d) 1.5 A |
