Question

You might have a flashlight that runs (2) d-cells of 1.5 volts each in series. the bulb is rated for 0.7 amps. what’s its resistance?

Answer 1

From Ohm's law, we get the general equation that would relate the voltage, current, and resistance,
                                  V = I x R
where V is voltage, R is resistance, and I is current. Deriving the equation for R
                                       R = V / I
                              R = (1.5 volts) / (0.7 amps) = 2.14 Ohms

Answer 2

Answer:

The value of resistance is 4.28 Ω.

Explanation:

Voltage of single d-cells = 1.5 V

Two d-cells are in series with in a flashlight.

$V_1= 1.5 V, V_2=1.5 V$

$V= V_1+V_2...V_n$ (series arrangement)

So, Total voltage in the flash light:

V = 1.5 V + 1.5 V = 3.0 V

Electrical Current rating of the bulb I= 0.7 A

let the resistance be R

$V=I\times R$ (Ohms law}

$R=\frac{V}{I}=\frac{3.0 V}{0.7 A}=4.28 \Omega$

The value of resistance is 4.28 Ω.