Question

8) If the resistance in an electrical circuit is held constant, the amount of current flowing through the 8) circuit is directly proportional to the amount of voltage applied to the circuit. When 2 volts are

applied to a circuit, 40 milliamperes of current flow through the circuit. Find the new current if the voltage is increased to 4 volts.
A) 100 milliamperes B) 76 milliamperes C) 80 m

Answer 1

C) 80 milliamperes

Explanation:

The amount of current flowing through a circuit is directly proportional to the amount of voltage applied across the circuit. The relation between current(I) and voltage(V) can be expressed as:

`I \propto V\\\\I = (1)/(R)V`

Here,
`(1)/(R)` is the proportionality constant. It is given that, when voltage is 2 volts, 40 milliamperes(
`40 * 10^(-3)` amperes) current flow through the circuit. Using these values we can find the value of proportionality constant. i.e.

`40 * 10^(-3)=(1)/(R) * 2\\\\ (1)/(R)=20 * 10^(-3)`

Using this value, we can establish the relation between I and V as:

`I = 20 * 10^(-3) * V`

Now, we need to calculate value current (I) if voltage is equal to 4 volts. Substituting V = 4 in above equation, we get:

`I = 20 * 10^(-3) * 4\\\\ I = 80 * 10^(-3)`

Thus, the value of current will be 80 milliamperes