(Multiple choice)

(1)

Two wires of the same material with the same length have different diameters. Wire A has twice the diameter of wire B. If the resistance of wire B is R, then what is the resistance of wire A? 

(a) R 

(b) 2R 

(c) R/2 

(d) 4R 

(e) R/4

(2)

A metal bar is to be used as a resistor. Its dimensions are 2 by 4 by 10 units. To get the smallest resistance from this bar, one should attach leads to the opposite sides that have the dimensions of 

(a) 2 by 4 units. 

(b) 2 by 10 units. 

(c) 4 by 10 units. 

(d) All connections will give the same resistance. 

(e) None of the above is correct.

(3)

Two cylindrical copper wires have the same mass. Wire A is twice as long as wire B. Their resistances are related by 

(a) R_A = 8R_B. 

(b) R_A = 4R_B. 

(c) R_A = 2R_B. 

(d) R_A=R_B.

(4)

A resistor carries a current I. The power dissipated in the resistor is P. What is the power dissipated if the same resistor carries current 3 I? (Assume no change in resistance.) 

(a) P 

(b) 3P 

(c) P/3 

(d) 9P 

(e) P/9

(5)

The power dissipated in a resistor is P when the voltage drop across it is V. If the voltage drop is increased to 2 V (with no change in resistance), what is the power dissipated? 

(a) P 

(b) 2P 

(c) 4P 

(d) P/2 

(e) P/4

(6)

Two resistors dissipate the same amount of power. The potential drop across resistor A is twice that across resistor B. If the resistance of resistor B is R, what is the resistance of A? 

(a) R 

(b) 2R 

(c) R/2 

(d) 4R 

(e) R/4

(7)

Two resistors are connected in parallel across a potential difference. The resistance of resistor 

A is twice that of resistor B. If the current carried by resistor A is I, then what is the current carried by B? 

(a) I 

(b) 2I 

(c) I/2 

(d) 4I 

(e) I/4

(8)

Two resistors are connected in series across a potential difference. Resistor A has twice the resistance of resistor B. If the current carried by resistor A is I, then what is the current carried by B? 

(a) I 

(b) 2I 

(c) I/2 

(d) 4I 

(e) I/4

(9)

When two identical resistors are connected in series across the terminals of a battery, the power delivered by the battery is 20 W. If these resistors are connected in parallel across the terminals of the same battery, what is the power delivered by the battery? 

(a) 5W

(b) 10W

(c) 20W

(d) 40W

(e) 80W