Question
Physics Question on Moving charges and magnetism
A uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of electrons is doubled, then the radius of the circular path will be
A
2.0 cm
B
0.5 cm
C
4.0 cm
D
1.0 cm
Answer
4.0 cm
Explanation
Solution
r=qBmv or r∝v
As v is doubled, the radius also becomes doubled.
Hence radius = 2 x 2 = 4 cm.