A hair dryer uses 10A at 120V. It is used with a transformer in England, where the voltage is 240V. A. What should be the ratio of the turns of the transformer? B. What current will the hair dryer now draw?

A. Np/Ns = 240 /120 = 2/1 = Turns ratio.

Np = Turns on primary winding.
Ns = Turns on secondary winding.

B. Pr = VI = 120 * 10 = 1200W = rated
power.

240I = 1200W,
I = 1200/ =240 = 5Amps.

Thanks Henry

A. Well, since you asked me for the ratio of turns, I guess we'll have to get a bit "twisted." Just like your hair in a hair dryer! *wink* Anyway, let's calculate it. The voltage ratio is given by:

\( \text{Voltage Ratio} = \frac{\text{Secondary Voltage}}{\text{Primary Voltage}} \)

So, in this case, the voltage ratio would be:

\( \text{Voltage Ratio} = \frac{240V}{120V} \)

B. As for the current that the hair dryer will now draw, let me dry it up for you. Since we know the voltage ratio, we can use the following equation to find the current ratio:

\( \text{Current Ratio} = \frac{\text{Primary Voltage}}{\text{Secondary Voltage}} \)

Plugging in the values, we get:

\( \text{Current Ratio} = \frac{120V}{240V} \)

Now, to find the current that the hair dryer will now draw, we just multiply the current it originally drew by the current ratio. So:

\( \text{Current in England} = \text{Original Current} \times \text{Current Ratio} \)

And voila! You've got your answer. Just remember, don't try drying your hair using an actual transformer. That's just shocking!

A. To find the ratio of the turns of the transformer, we can use the formula:

Voltage ratio = Turns ratio

Given:
Primary voltage (US) = 120V
Secondary voltage (England) = 240V

Using the formula, we have:

Turns ratio = Secondary voltage / Primary voltage

Turns ratio = 240V / 120V
Turns ratio = 2

Therefore, the ratio of the turns of the transformer should be 2:1.

B. The current drawn by the hair dryer will change when the voltage changes, according to Ohm's Law, which states:

Current = Voltage / Resistance

Given:
Current (US) = 10A (Since the hair dryer uses 10A at 120V)
Voltage (England) = 240V

Using Ohm's Law:

Current (England) = Voltage (England) / Resistance

We need to calculate the new resistance, so we rearrange the formula:

Resistance = Voltage (US) / Current (US)

Resistance = 120V / 10A
Resistance = 12Ω

Now, we can find the current in England:

Current (England) = 240V / 12Ω
Current (England) = 20A

Therefore, the hair dryer will draw a current of 20A when used with the transformer in England.

To determine the ratio of turns on the transformer, you can use the concept of transformer turns ratio, which is defined as the ratio of the number of turns on the primary side (input) to the number of turns on the secondary side (output).

A. The voltage ratio of the transformer is equal to the turns ratio. Since the voltage in England is 240V and the input voltage is 120V, the turns ratio should be:

Turns ratio = Output Voltage / Input Voltage
Turns ratio = 240V / 120V
Turns ratio = 2

Therefore, the ratio of turns on the transformer should be 2:1.

B. To calculate the current the hair dryer will draw when used with the transformer, we can use the principle of power conservation in a transformer. The power consumed by the hair dryer before and after the transformation must be the same.

Power = Voltage x Current

Before transformation:
Power (before) = 120V x 10A = 1200W

After transformation:
Power (after) = 240V x I (current with transformer)

Since the power is conserved, we can equate the two expressions:

1200W = 240V x I

Solving for I (current with transformer):
I = 1200W / 240V
I = 5A

Therefore, the hair dryer will draw a current of 5A when used with the transformer in England.