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(i) What happens to the magnitude of the magnetic field inside a long solenoid i

ID: 2011230 • Letter: #

Question

(i) What happens to the magnitude of the magnetic field inside a long solenoid if the current is doubled?
a.It becomes four times larger.
b.It becomes twice as large.
c.It is unchanged.
d.It becomes one-half as large.
e.It becomes one-fourth as large.

(ii) What happens to the field if instead the length of the solenoid is doubled, with the number of turns remaining the same?
a.It becomes four times larger.
b.It becomes twice as large.
c.It is unchanged.
d.It becomes one-half as large.
e.It becomes one-fourth as large.

(iii) What happens to the field if the number of turns is doubled, with the length remaining the same?
a.It becomes four times larger.
b.It becomes twice as large.
c.It is unchanged.
d.It becomes one-half as large.
e.It becomes one-fourth as large.

(iv) What happens to the field if the radius is doubled?
a.It becomes four times larger.
b.It becomes twice as large.
c.It is unchanged.
d.It becomes one-half as large.
e.It becomes one-fourth as large.

Explanation / Answer

The magnetic field inside the solenoid is             B = o nI Here n = N/l Here I be the current          N be the number of turns           l be the length of solenoid           i) It becomes twice as large. That is option (b) is correct. ii) d.It becomes one-half as large. Option (d) is correct. iii) b.It becomes twice as large . Option (b) is correct. iv) Here magnetic field is independent of radius so "c) it is unchanged"