Resistance

Question 1

What is Resistance measured in?

Answer 1

Ohms

Question 2

What is one Ohm equivalent to?

Answer 2

one ohm is the equivalent of one kilogram meter squared per second cubed per ampere(An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor) squared

Question 3

Why would the resistance in a wire increase?

Answer 3

• The length of the wire increases

- The thickness of the wire decreases

Question 4

Does a thin wire have high or low resistance?

Answer 4

High.

Question 5

Does a thick wire have high or low resistance?

Answer 5

Low.

Question 6

What causes resistance?

Answer 6

An electric current flows when electrons move through a conductor, for example a metal wire. The moving electrons collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.

Question 7

Which has more resistance a long wire or a short wire? Why?

Answer 7

The resistance of a long wire is greater than the resistance of a short wire because electrons collide with ions more often.

Question 8

Which has more resistance a thin wire or a thick wire? Why?

Answer 8

The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current.

Question 9

What is the equation for resistance?

Answer 9

V = I × R
V-is the potential difference in volts, V
I-is the current in amperes (amps), A
R-is the resistance in ohms, Ω
The equation can be rearranged to find the resistance:
R = V ÷ I

Question 10

What is a filament lamp?

Answer 10

A light bulb that contains a thin coil of wire called the filament. This heats up when an electric current passes through it, and produces light as a result.

Question 11

What is a Diode?

Answer 11

Diodes are electronic components which can be used to regulate the potential difference in circuits and to make logic gates. The diode has a very high resistance in one direction.

Question 12

What is LED? What are they used in?

Answer 12

A light-emitting diode, produces light when a current flows through it in the forward direction. LEDs are often used for indicator lights in electrical equipment such as computers and television sets. As LEDs use a much smaller current than other types of lighting, their use is increasing.

Question 13

What is a Thermistor?

Answer 13

Thermistors are used as temperature sensors - for example, in fire alarms.

Question 14

What is the resistance of a Thermistor in high and low temperatures?

Answer 14

At low temperatures, the resistance of a thermistor is high and little current can flow through them.
At high temperatures, the resistance of a thermistor is low and more current can flow through them.

Question 15

What are LDRs (light-dependent resistors) used in?

Answer 15

LDRs are used to detect light levels, for example, in automatic security lights.

Question 16

What is the resistance of LDRs in dark and in bright light?

Answer 16

In the dark and at low light levels, the resistance of an LDR is high and little current can flow through it.
In bright light, the resistance of an LDR is low and more current can flow through it.