Question

Thanks for any help :)

Four 20 ohm resistors are connected in parallel and the combination is connected to a 20V emf device. The current is:
A) 0.25A
B) 1.0 A
C) 4.0 A
D) 5.0 A
E) 100 E

Parallel circuits:
I know that the voltage is 20V and the Resistance is 20 V. So, I divided I=V/R
I= (20/20)=1 The current for a parallel circuit is found by I= I + I+ I+I
The current is 1 so therefore I total would be 4 or C.

Four 20 ohm resistors are connected in series and the combination is connected to a 20V emf device. The potential difference across any one of the resistors is:
A) 1 V
B) 4 V
C) 5 V
D) 20V
E) 80 V

So there are four resistors that are 20 ohms. Their connected to a 20 V device. The question wants to known volts. Its says for a parallel circuit. I just dividied 20V/4 and got 5V.Is that ok to think of it that way?

Thank you

correct on the first. However, if the second circuit is parallel, each resistor has 20V across it.

Answer 1

A potential difference of 2.0 V is applied across a wire of cross sectional area 2.5 mm^2. The current which passes through the wire is 3.2 × 10-3 A. What is the resistance of the wire?

Answer 2

For parallel circuit the formula is:
1/Req= 1/Rn....
And there are 4 resistors of 20
So
1/Req= 1/20+1/20+1/20+1/20
1/Req= 4/20
Req/1= 20/4= 5
For the current formula is:
I=V/R
V= 20 given
I= 20/5= 4 so the answer is 4