The magnetic field produced by a long straight current-carrying wire is a) inversely proportional to the current in the wire and proportional to the distance from the wire. b) inversely proportional to both the current in the wire and the distance from the wire. c) proportional to both the current in the wire and the distance from the wire d) proportional to the current in the wire and inversely proportional to the distance from the wire. e) independent of both the current in the wire and the distance from the wire.

The magnetic field produced by a long straight current-carrying wire is directly proportional to the current in the wire and inversely proportional to the distance from the wire.

Explanation:

The magnetic field produced by a long straight current-carrying wire is given by :

............(1)

Where

= permeability of free space,

I = current flowing in the wire

d = distance from wire

From equation (1), it is clear that the magnetic field produced by a long straight current-carrying wire is directly proportional to the current flowing and inversely proportional to the distance from the wire. So, the correct option is (d).

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000