Lesson 12: The Electrical Circuit and Ohm's Law

A circuit has an operating voltage of 220 volts. The circuit resistance is 55 ohms which limits the current to 4 amperes. You wish to add enough resistance to limit the current to 2 amperes. How much total resistance would you need in this circuit?

110 Ω

The value 120 kV is equal to ? .

120,000 V

An electric heater has a resistance of 15.31 ohms and draws 7.84 amperes of current. What is the circuit voltage? (Round the FINAL answer to two decimal places.)

120.03 V

An electric heater has a resistance of 17.32 ohms and requires a current of 6.93 amperes. What is the circuit voltage? (Round the FINAL answer to two decimal places.)

120.03 V

A lamp operates on 300 volts and draws 25 milliamps. What is the resistance?

12000 Ω

A lamp operates at 120 volts and requires 0.83 amps of current when operating. What is the resistance of this lamp? (Round the FINAL answer to two decimal places.)

144.58 Ω

The value 200,000 ohms can also be expressed as ? .

200 kΩ

How much current will flow through a 2.4 kilohm resistor when 7.2 kilovolts is applied?

3 A

A heater operates at 240 volts and has a resistance of 28 ohms. How much current will flow in the circuit when the heater is turned on? (Round the FINAL answer to two decimal places.)

8.57 A

What mathematical equation is used where I and R are known, and E is to be determined?

E = I x R

A circuit is defined as a completed path for voltage to flow from a source of voltage through a load and back to the source.

False

For a given circuit, if the resistance is decreased, the net result will be a decrease in current flow by the same percent, and thus the current is inversely related to the resistance in the circuit.

False

Ohm's Law states that it takes 1 amp to push 1 ohm of resistance through 1 volt.

False

When a circuit is open, voltage does not exist in the circuit.

False

What mathematical equation is used where E and R are known, and I is to be determined?

I = E / R

Match the correct response for a given circuit.

If you raise R, I will go ? . → down If you raise E, I will go ? . → up If you lower E, I will go ? . → down If you lower R, I will go ? . → up

Resistance in a circuit and in Ohm's Law is represented by the letter ? .

R

What mathematical equation is used where E and I are known, and R is to be determined?

R = E / I

Before current can flow in a circuit, the circuit must be closed.

True

For a given circuit, if the source voltage is increased, the current flowing through the resistance increases by the same percent, and thus is directly proportional.

True

Prefix multipliers are used to simplify the printing and use of small or large figures.

True

The metric prefix for 1,000,000 is Mega or M.

True

True

When using the pie diagram, cover the factor I, E, or R, you wish to determine. The diagram will then indicate if the other two factors are multiplied together, or if one is divided into the other.

The value 0.000001 Amp can also be expressed as ? .

a. or c.

A complete circuit or path is often referred to as a(n) ? circuit.

closed

When current does not flow in a circuit, it is called a(n) ? circuit.

open

A short circuit causes a drastic decrease in the ? of the circuit and could cause the ? to be dangerously high.

resistance / current flow

Many non-electrical people often call an open circuit a(n) ? circuit.

short

When current finds an alternate path back to the source, rather than taking a path through the load, it is called a(n) ? circuit.

short

Current flow in an electrical circuit is caused by ? and opposed by ? .

voltage / resistance

The metric prefix for Micro is ? .

µ