Chapter 10
Problems
Please turn in problems on a separate sheet of paper, & show your work.
26.
A light bulb draws a current of 2 amps when connected to a wall outlet (120 V).
What is the resistance and wattage of the bulb?
27.
What is the cost of running a 1500-W hair dryer for 30 minutes, when the cost of electricity is
$ 0.12/kWh?
28.
A 12-V battery is connected across a device whose resistance is 24 ohms.
Calculate the current in the wire.
What is the power dissipated by this load?
29.
How much current is drawn by a 1000-W electric skillet operating on 120 V?
30.
With a 1200-W toaster, how much electrical energy is needed to make a slice of toast (cooking time 5 1
minute)?
At $.08/kWh, how much does this cost?
35.
A 50-ohm resistor is connected across 120 V.
How much heat is dissipated in the resistor?
36.
Resistors of 10 and 30 ohms are connected in series to a 120-V source.
What is the current flowing in the 30 ohm resistor?
What is the current in this resistor when the same resistors are connected in parallel?
38.
Most of the body’s resistance is in its skin.
When wet, salts go into ion form, and the resistance is lowered.
Compare the current that would pass through a person who comes into contact with a 240-V source
when there is:
(a) a dry skin resistance of 100,000 ohms.
(b) a wet skin resistance of 300 ohms.