A Hall Voltage of 15 $\mu$ V Is Measured Across a 4

Multiple Choice

A Hall voltage of 15 $\mu$ V is measured across a 4.0-mm side of a metal slab immersed in a magnetic field whose strength is 0.150 T. The average velocity of the charges is

A) 2.5 cm/s.
B) 5.0 cm/s.
C) 7.5 cm/s.
D) The value cannot be obtained from the information given.