Physics-16 Electrical Circuits PreQuiz

An electrical device that resists the flow of electrical current:

• resistor

• light-dependent resistor (LDR)

• NTC thermistor

• relay

• diode

Answer explanation

A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.

what is an electrical component with a resistance that decreases as the light intensity incident on it increases?

• resistor

• light-dependent resistor (LDR)

• NTC thermistor

• relay

• diode

Answer explanation

A photoresistor or light dependent resistor is an electronic component that is sensitive to light. When light falls upon it, then the resistance changes. Values of the resistance of the LDR may change over many orders of magnitude the value of the resistance falling as the level of light increases.

What is a resistor whose resistance decreases with increasing temperature?

• resistor

• light-dependent resistor (LDR)

• NTC thermistor

• relay

• diode

Answer explanation

NTC stands for "Negative Temperature Coefficient". NTC thermistors are resistors with a negative temperature coefficient, which means that the resistance decreases with increasing temperature.

What is a switch controlled by an electromagnet?

• resistor

• light-dependent resistor (LDR)

• NTC thermistor

• relay

• diode

Answer explanation

A relay is an electrical device, typically incorporating an electromagnet, which is activated by a current or signal in one circuit to open or close another circuit.

What is device that permits current to flow through it in only one direction?

• resistor

• light-dependent resistor (LDR)

• NTC thermistor

• relay

• diode

Answer explanation

A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction.

What is it when the case of an electrical appliance is connected to the earth wire (for safety)?

• earthed

• Double insulated

• trip switch

• Potential divider

• Light Emitting Diode (LED)

Answer explanation

To Earth is to connect (an electrical device) with the ground. (grounded in US English).

Being ____ _____ is having an outer casing which is an electrical insulator; having no exposed metal casing.

• earthed

• Double insulated

• trip switch

• Potential divider

• Light Emitting Diode (LED)

Answer explanation

Double or reinforced insulation is another method of protection against electric shock, consisting of an extra layer of supplementary insulation over the basic insulation, or a single layer of special reinforced insulation directly over the live parts.

What is a device used to protect an electric circuit in case of an electrical fault?

• earthed

• Double insulated

• trip switch

• Potential divider

• Light Emitting Diode (LED)

Answer explanation

A Trip switch is an electric switch arranged to interrupt a circuit suddenly and disconnect power from a running machine so that the machine is stopped.

A _____ ____ is two resistors placed in series that divide up the battery's potential difference (R1 / R2 = V1 / V2).

• earthed

• Double insulated

• trip switch

• Potential divider

• Light Emitting Diode (LED)

Answer explanation

A potential divider is a simple circuit that uses resistors to supply a variable 'potential difference' (i.e. voltage). This can be used for many applications, including control of temperature in a fridge or as audio volume controls.

What is a diode that will produce light when current flows

through it?

• earthed

• Double insulated

• trip switch

• Potential divider

• Light Emitting Diode (LED)

Answer explanation

A Light Emitting Diode (LED) is a semiconductor device, which can emit light when an electric current passes through it. To do this, holes from p-type semiconductors recombine with electrons from n-type semiconductors to produce light.