Unit D Section 2.2

Question 1

Current modelled by water?

Answer 1

Current= Amount of water (The more electrons, the more powerful the current).

Question 2

Voltage modeled by water?

Answer 2

Voltage= water pressure (If you pump water up a hill, it gains gravitational potential energy, and then flows back down= a battery, or generator “pumps” electrons to a point with a higher electric potential (voltage)

Question 3

Resistance modeled by water?

Answer 3

Resistance= rocks (like water smashes into rocks, electrons encounter resistance)

As with water flow, you get the least resistance with a short, wide path with no obstructions. The shorter and thicker the wire, the less resistance it creates for electrons

The flow of current will be reduced if it has to pass through a resistor.

Question 4

Electricity cell of generator modeled by water?

Answer 4

The melting snow keeps the stream flowing. For electricity, a source such as a generator or a cell keeps the electricity flowing from a negatively charged terminal to a positively charged one.

But if all the snow was melted, the river will eventually stop just like if a generator is shut down or a cell is used up, electricity will stop flowing.

Question 5

2 things Ohm’s law states as long as the temperature stays the same:

Answer 5

The resistance of the conductor stays constant

If you increase the voltage in the circuit, the current also increases.

Question 6

The triangle for ohm’s law

Answer 6

V

I R

Question 7

The calculation to find voltage?

Answer 7

V= I x R

Question 8

The calculation to find current?

Answer 8

I= V/R

Question 9

The calculation to find the resistance?

Answer 9

R= V/I

Question 10

Steps for ohm’s law

Answer 10

Steps for calculating:
Step 1: Identify known quantities.
Step 2:Identify the unknown quantity resistance (R)
Step 3: Use the formula.
Step 4: calculate

Question 11

How is ohm’s law calculation not always accurate?

Answer 11

Calculations may not be perfect because if the temperature of a resistor changes, its resistance changes as well.
resistance is lowest when a conductor is cool. As the temperature increases, resistance increases.
For example: a light bulb is receiving ten times more than its normal current which means the filament (resistor) heats up therefore resistance increases and decreases the amount of current.

Question 12

Voltage drop:

Answer 12

is the amount of voltage loss that occurs through a circuit due to any obstructions or resistance. It occurs more in a series circuit but not in a parallel circuit.

Question 13

Millivolt Meters:

Answer 13

measure small volts. One millivolt is equal to 1/1,000 of a volt.

Question 14

Voltmeter:

Answer 14

measures volts or potential difference across a cell, battery, resistor, or other device in a circuit.

Question 15

Ammeters:

Answer 15

Device that is used to measure electric current in amperes.

It is a measure of how many electrons move past a point in a circuit each second

An ammeter must be placed so that the current flows through it to measure.

The current is the same at every point in the loop, so the ammeter can measure it anywhere. Mostly placed between two components in the circuit.

Question 16

Galvanometers:

Answer 16

A device that measures small currents.

Question 17

Multimeters:

Answer 17

Can measure voltage, amperage and resistance.

Question 18

Factors that affect resistance:

Answer 18

Length: Resistance increases with length.

Diameter thickness (cross section area): Resistance decreases as area increases.

Temperature: as temperature of wire increases, resistance increases.

Materials: some metals allow electrons to move more easily.