Multiple Choice
The figure shows a 2.0-cm diameter roller that turns at 90 rpm. A 4.0-cm wide plastic film is being wrapped onto the roller, and this plastic carries an excess electric charge having a uniform surface charge density of 5.0 nC/cm2. What is the current of the moving film? 
A) 190 nA
B) 23 μA
C) 30 nA
D) 11 μA
Correct Answer:
Verified
Correct Answer:
Verified
Q5: A wire has a cross-sectional area of
Q11: Calculate the current through a 10.0-m long
Q13: If the current density in a wire
Q17: Nichrome wire,often used for heating elements,has resistivity
Q23: A certain fuse "blows" if the current
Q24: In an electroplating process, copper (ionic charge
Q27: When a voltage difference is applied to
Q30: The diameter of a 12-gauge copper wire
Q31: What must be the diameter of a
Q37: When a potential difference of 10 V