When an electron moving with a uniform speed in a vacuum enters a magnetic field in a direction perpendicular to the field the subsequent path of the electron is ___________________?

When an electron moving with a uniform speed in a vacuum enters a magnetic field in a direction perpendicular to the field the subsequent path of the electron is ___________________?

A. a straight line parallel to the field
B. a parabola in a plane perpendicular to the field
C. a circle in a plane perpendicular to the field
D. a straight line along its initial direction

While measuring the unknown resistance the help of slide wire bridge a greatest accuracy can be achieved when__________________?

While measuring the unknown resistance the help of slide wire bridge a greatest accuracy can be achieved when__________________?

A. a most sensitive galvanometer is used
B. a steady voltage cell is used
C. the balance point is close to the middle of the wire
D. a high resistance box is used in one of its gap