Question

A motor uses 50 W of power and draws a current of 400 mA. (a) What is voltage across the motor ? (b) What is the internal resistance of the motor? ​

Answer 1

Ответ:

Объяснение:

Дано:

P = 50 Вт

I = 400 мА = 0,4 А

_____________

U - ?

R - ?

Напряжение:

U = P / I = 50 / 0,4 = 125 вольт

Сопротивление:

R = U / I = 125 / 0,4 ≈ 300 ом.

____________

Given:

P = 50 W

I = 400 mA = 0.4 A

_____________

U -?

R -?

Voltage:

U = P / I = 50 / 0.4 = 125 volts

Resistance:

R = U / I = 125 / 0.4 ≈ 300 ohm.

Answer 2

To determine the voltage across the motor and the internal resistance of the motor, we can use Ohm's Law and the power formula.

(a) What is the voltage across the motor?

Ohm's Law states that V (voltage) is equal to the product of the current (I) and the resistance (R): V = I * R.

In this case, we have the power (P) and the current (I), and we want to find the voltage (V). First, we need to calculate the resistance (R):

1. Convert the current to amperes (A): 400 mA = 0.4 A

2. Use the power formula to find the resistance: P = V^2 / R

   Rearrange the formula to solve for resistance (R): R = V^2 / P

   Plug in the values: R = (V^2) / (50 W)

Now, we can find the resistance (R):

R = (V^2) / (50 W)

0.4 A = (V^2) / (50 W)

Now, solve for V:

V^2 = 0.4 A * 50 W V^2 = 20 VA V = √(20 VA) V ≈ 4.47 V

So, the voltage across the motor is approximately 4.47 volts.

(b) What is the internal resistance of the motor?

We already have the voltage (V) and current (I), and we can use Ohm's Law to find the internal resistance (R_internal):

R_internal = V / I R_internal = 4.47 V / 0.4 A R_internal = 11.175 ohms

So, the internal resistance of the motor is approximately 11.175 ohms.