Advertisements
Advertisements
प्रश्न
A straight metal wire crosses a magnetic field of flux 4 mWb in a time 0.4 s. Find the magnitude of the emf induced in the wire.
Advertisements
उत्तर
Given data:
dΦ = 4 mWb = 4 × 10-3
dt = 0.4 s
induced emf ε = ?
ε = + `("d"phi)/"dt"`
`therefore = (4 xx 10^-3)/0.4 = 40/4 xx 10^-3`
ε = 10 mV
APPEARS IN
संबंधित प्रश्न
A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.
A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm s−1 in a direction normal to the
- longer side,
- shorter side of the loop?
For how long does the induced voltage last in each case?
Explain why, the core of an electromagnet should be of soft iron and not of steel.
When a wire is moved up and down in a magnetic field, a current is induced in the wire. What is this phenomenon known as?
The switches in figure (a) and (b) are closed at t = 0 and reopened after a long time at t = t0.


(a) The charge on C just after t = 0 is εC.
(b) The charge on C long after t = 0 is εC.
(c) The current in L just before t = t0 is ε/R.
(d) The current in L long after t = t0 is ε/R.
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
D.C. motor ______.
A transformer has 400 turns in the primary winding and 10 turns in the secondary winding. The primary e.m.f. is 250 V and the primary current is 2.0 A. calculate:
(a) The secondary voltage,
(b) The secondary current, assuming 100% efficiency.
What is an electromagnet?
If the sun radiates energy at the rate of 3.6 × 1033 ergs/sec the rate at which the sun is loosing mass is given by ______.
A galvanometer is an instrument that can detect the presence of a current in a circuit.
