Question

elp with physics 102

An electron moves through a region of crossed electric and magnetic fields. The electric field E = 2 000 V/m and is directed straight down. The magnetic field B = 0.80 T and is directed to the left. Specify the directions of electric and magnetic forces on the electron if it moves into the paper. For what velocity v of the electron will the electric force exactly cancel the magnetic force? A rod(length = 10 cm) moves on two horizontal frictionless conducting rails, as shown. The magnetic field in the region is directed perpendicularly to the plane of the rails (into the paper) and is uniform (does not change from point to point) and constant ( does not change with time). If a constant force of 0.60 N to the right moves the bar at a constant speed of 2.0 m/s, what is the current through the 12-ohm resistor?

Answer 1

Answer 2

1. V = E/B = 2000/0.8 = 2500

Answer 3

according to right hand rule inorder to find out the force
due to magnetic field

The right hand rule states that:
to determine the direction of the magnetic force on a positive moving charge, f,
point the thumb of the right hand in the direction of v,
the fingers in the direction of B,
and a perpendicular to the palm points in the direction of F.

here we get the direction as upwards but since electron is a
negative charge .

magnetic force direction is downwards ie., in the direction of electric field

electric force direction is the same as that of electric field direction for
a positive charge. since here the charge electron is negative the direction
is opposite to that of electric field.

so electric force direction : upwards
magnetic field direction : downwards

magnetic force = qvB
electric force = qE

equationg we get vB = E
v = E/B = 2000/0.8 = 2500 m/s

Answer 4

zina te charga on slest is nasah Oprectiom ninca direchm 202500 m/ 0.9 ②一. Since the rod L writh contant velo 0.6 X12 2