Pysics about current in circuit

Question

Two circuits have the same resistance. The potential in Circuit A is 3 times of that in Circuit B, but its current is only 0.6A greater than Circuit B. What is the current in Circuit B?

Answer 1

Dear Student,

The equation for the potential difference is potential difference = current × resistance, or, V=IR. 

In circuit A we have: 3V=(I+.6)R

The resistance, therefore, equals, (3V)/(I+.6)=R.

Since the circuit has the same resistance, we must now find a value for the current in circuit B that will be the same resistance.

In circuit B we have V=IR

(V)/(I)=R

we replace R with (3V)/(I+.6) so now

(V)/(I)=(3V)/(I+.6).

If you cross multiple you get: 3VI=VI+.6V

Subtract VI from both sides: 2VI = .6V

Cross out the V's: 2I=.6

Divide both sides by 2: I=.3

That means the current in circuit B is .3.

You can check this answer by making sure the resistance is the same in both circuits.

If the current in B is .3, in A it has to be .9.

To check plug into V=IR equation,

For A:

3=.9R

R= 10/3

For B:

1=.3R

R= 10/3

So it confirms that the current for Circuit B is .3A.

Hope this helps!