A step-up transformer has a primary coil with 100 loops and a secondary coil with 1,500 loops. If th

1. A swimming pool requiring a 2.0 hp motor to filter and circulate the water runs for 18 hours a day. What is the monthly electrical cost for running this pump if electricity costs 10 cents per kWh?

2. Is it possible for two people to simultaneously operate 1,300 W hair dryers on the same 120 V circuit without tripping a 15 A circuit breaker? Explain.

3. What is the force between two balloons with a negative charge of 1.6X10 -10 ?

4. An inflated balloon is rubbed with a wool cloth until an excess of a billion electrons is on the balloon. What is the magnitude of the charge on the balloon?

5. A step-down transformer connected to a 120 V electric generator has 30 loops on the primary for each loo0p in the secondary. (a) What is the voltage of the secondary? (b) If the transformer has a 90 A current in the primary, what is the current in the secondary? (c) What are the power input and output?

A step-up transformer has a primary coil with 100 loops and a secondary coil with 1,500 loops. If the primary

Your question about the 100:1500 step-up transformer got cut off, so I can't help you with that one.

1. First, convert the 2.0 horsepower into kiloWatts. Call this value "P", the power of the motor.

The monthly energy use is:

kW-hr / month =

P x (18 hrs/day) x (# of days per month)

For # of days per month, you could just use 30.

Finally, take this number and multiply it by 0.10 $/kW-hr, to get the monthly cost in $.

2. First, figure out how much power P the circuit can handle:

P = V I

where V=120V and I=15A.

Next, use the fact that two 1300W dryers is a total power of 2600W. Is 2600W more than or less than the number you just calculated from the P = V I equation?

3. Not answerable. It depends on how far apart the baloons are from each other.

4. Look up the charge of a single electron. It is probably listed on the inside back or front cover of your textbook.

Next, multiply that value times one billion.

5. This is a 30:1 step-down transformer.

(a) The secondary voltage is (1/30) times the input voltage of 120V.

(b) The secondary current will be 30 times the current in the primary, ignoring losses due to the resistance of the wires.

(c) The input and output powers are equal, again ignoring losses due to the resistance of the wires. To find the value, use

P = V I

for either the primary or secondary.