Electronics Information · Practice test 2

Question 1Not answered

What current flows when 18 volts is applied across 3 ohms?

1. 6 amperes
2. 54 amperes
3. 0.17 amperes
4. 15 amperes

Question 2Not answered

A semiconductor is a material that

1. conducts better than an insulator but worse than a metal
2. conducts electricity better than any metal
3. blocks current completely under all conditions
4. stores charge instead of carrying current

Question 3Not answered

Connecting several identical cells in parallel, rather than in series, mainly increases the battery's

1. available current and running time at the original voltage
2. output voltage while current stays the same
3. output voltage and current together
4. internal resistance well above a single cell

Question 4Not answered

A resistor rated at 2 watts safely carries 0.5 ampere. What is the highest resistance it could have at that current without exceeding its rating?

1. 8 ohms
2. 4 ohms
3. 1 ohm
4. 16 ohms

Question 5Not answered

To read the current in a circuit, an ammeter must be connected

1. in parallel, across the component being tested
2. between the live conductor and ground
3. in series, so all the current passes through it
4. with the circuit power switched off

Question 6Not answered

A fuse protects a circuit by

1. absorbing the extra current until it subsides
2. reducing the supply voltage automatically
3. melting and breaking the circuit when current is too high
4. diverting the current into the neutral wire

Question 7Not answered

The period of an alternating waveform is

1. the number of cycles in one second
2. the time taken for one complete cycle
3. the highest voltage the wave reaches
4. the average voltage over one cycle

Question 8Not answered

Power in a DC circuit is best defined as

1. the pressure driving current through a load
2. the rate at which electrical energy is converted to other forms
3. the opposition a load presents to current
4. the total charge stored in a capacitor

Question 9Not answered

A potentiometer is a type of

1. variable resistor
2. fixed capacitor
3. one-way valve for current
4. magnetic switch

Question 10Not answered

How many terminals does a standard transistor have?

1. Two
2. Four
3. One
4. Three

Question 11Not answered

In an NPN bipolar transistor, applying a small forward current to the base allows

1. current to flow only from emitter to base
2. the transistor to store charge like a capacitor
3. the transistor to block all current between any terminals
4. a much larger current to flow between the collector and emitter

Question 12Not answered

A 20 ohm load is connected to a 240 volt supply. What current flows?

1. 4800 amperes
2. 260 amperes
3. 0.08 amperes
4. 12 amperes

Question 13Not answered

Before using an ohmmeter to test a resistor mounted in a circuit, you should first

1. remove power from the circuit
2. increase the circuit's supply voltage
3. connect the meter in series with the load
4. short the resistor's leads together

Question 14Not answered

Four 5 ohm resistors are connected in series. What is the total resistance?

1. 1.25 ohms
2. 5 ohms
3. 625 ohms
4. 20 ohms

Question 15Not answered

The severity of an electric shock depends most directly on

1. the amount of current passing through the body
2. the voltage marked on the supply
3. the total power the circuit can deliver
4. whether the current is direct or alternating

Question 16Not answered

When working around energized electrical equipment, standing on a dry rubber mat mainly helps by

1. adding a high-resistance barrier between the worker and the ground
2. increasing the current available to the equipment
3. grounding the worker more effectively
4. lowering the equipment's operating voltage

Question 17Not answered

Connecting the metal frame of test equipment to a common ground point is done mainly to

1. increase the voltage available to the equipment
2. reduce the resistance of the power supply
3. hold all connected equipment at the same reference voltage
4. convert the equipment's supply to direct current

Question 18Not answered

A device consumes 250 watts while drawing 2 amperes. What voltage is it operating at?

1. 125 volts
2. 500 volts
3. 252 volts
4. 62.5 volts

Question 19Not answered

A wire that offers exactly zero resistance to current flow is called

1. an insulator
2. a semiconductor
3. a superconductor
4. a resistor

Question 20Not answered

Electric current is measured in

1. volts
2. amperes
3. ohms
4. watts