Year 9 Circuits

Question 1

What are the two types of charges?

Answer 1

Positive (+) and negative (-)

Charges are fundamental properties of matter, with electrons carrying negative charge and protons carrying positive charge.

Question 2

What do electrons carry?

Answer 2

Negative charge

Electrons are subatomic particles that can be moved from atoms.

Question 3

How can objects be charged?

Answer 3

By transferring electrons through friction

This process involves rubbing two materials together, allowing electrons to move from one to the other.

Question 4

What characterizes neutral objects?

Answer 4

They have the same amount of positive and negative charge

Neutrality is achieved when the number of protons equals the number of electrons.

Question 5

How is an object made negative?

Answer 5

By gaining electrons

When an object acquires extra electrons, it takes on a negative charge.

Question 6

How is an object made positive?

Answer 6

By losing electrons

The loss of electrons results in a surplus of protons, leading to a positive charge.

Question 7

What happens when two objects with the same charge interact?

Answer 7

They repel each other

This repulsion occurs because like charges push away from each other.

Question 8

What happens when two objects with opposite charges interact?

Answer 8

They attract each other

Opposite charges pull towards each other due to the fundamental forces of electrostatics.

Question 9

What is the behavior of charged objects towards neutral objects?

Answer 9

They attract neutral objects

Charged objects can influence neutral objects, causing them to become polarized and attracted.

Question 10

What particles make up an atom?

Answer 10

Protons, neutrons, and electrons

Protons are positively charged, electrons are negatively charged, and neutrons have no charge.

Question 11

What is an electrical insulator?

Answer 11

A material through which electrons cannot flow

Insulators hold electrons tightly to their atoms, preventing electrical current.

Question 12

What happens when you rub a plastic rod with a cloth?

Answer 12

Electrons are transferred, creating a charge imbalance

This process results in one object becoming negatively charged and the other positively charged.

Question 13

What is the effect of friction on materials like glass and silk?

Answer 13

Electrons are transferred from the glass rod to the silk cloth

This transfer of electrons causes the silk to become negatively charged and the glass rod to become positively charged.

Question 14

What is the formula to calculate current?

Answer 14

Q = I x t

Q represents charge in Coulombs, I represents current in Amps, and t represents time in seconds.

Question 15

Calculate the current when 1 Coulomb of charge flows every 1 second.

Answer 15

1 Amp

Using the formula Q = I x t, where Q = 1 and t = 1.

Question 16

Calculate the current when 10 Coulombs of charge flows every 2 seconds.

Answer 16

5 Amps

Calculation: 10 ÷ 2 = 5.

Question 17

Calculate the current when 20 Coulombs of charge flows every 4 seconds.

Answer 17

5 Amps

Calculation: 20 ÷ 4 = 5.

Question 18

How many Coulombs of charge are transferred when a current of 5.5A flows for 14s?

Answer 18

77 Coulombs

Calculation: Q = 14 x 5.5.

Question 19

How many Coulombs of charge are transferred when a current of 0.6A flows for 0.8s?

Answer 19

0.48 Coulombs

Calculation: Q = 0.6 x 0.8.

Question 20

How many Coulombs of charge are transferred when a current of 8.9A flows for 1 minute?

Answer 20

534 Coulombs

Calculation: Q = 8.9 x 60.

Question 21

What is the function of a switch when it is in the open position?

Answer 21

It prevents current from flowing through the circuit.

An open switch creates a break in the circuit, stopping the flow of electricity.

Question 22

What happens to a switch when it is in the closed position?

Answer 22

It allows current to flow through the circuit.

A closed switch completes the circuit, enabling electrical flow.

Question 23

What is the role of a fuse in an electrical circuit?

Answer 23

To protect the circuit from excessive current by breaking the circuit.

Fuses are designed to melt and disconnect the circuit when the current exceeds a certain level.

Question 24

What is a cell in terms of electrical components?

Answer 24

A source of electrical energy that provides voltage.

Cells convert chemical energy into electrical energy.

Question 25

What instrument measures voltage in a circuit?

Answer 25

Voltmeter. ## Footnote Voltmeters are connected in parallel to measure the potential difference across components.

Question 26

What is the purpose of a battery?

Answer 26

To store and provide electrical energy. ## Footnote Batteries consist of one or more cells and are used as portable power sources.

Question 27

What does an ammeter measure?

Answer 27

Current flowing through a circuit. ## Footnote Ammeters must be connected in series to measure the current accurately.

Question 28

What is the function of a diode?

Answer 28

To allow current to flow in one direction only. ## Footnote Diodes are used for rectification in circuits.

Question 29

What is a thermistor?

Answer 29

A type of resistor whose resistance changes with temperature. ## Footnote Thermistors are often used in temperature sensing applications.

Question 30

What is the purpose of a resistor in a circuit?

Answer 30

To limit the flow of current. ## Footnote Resistors are used to control voltage and current levels in various components.

Question 31

What is a variable resistor?

Answer 31

A resistor whose resistance can be adjusted. ## Footnote Variable resistors are commonly used in applications like volume controls.

Question 32

What does LDR stand for?

Answer 32

Light Dependent Resistor. ## Footnote LDRs change their resistance based on the intensity of light falling on them.

Question 33

Fill in the blank: Two bulbs in _______ share the same current but have different voltages across them.

Answer 33

series. ## Footnote In a series circuit, components are connected end-to-end, and the same current passes through each component.

Question 34

What is the unit of resistance?

Answer 34

Ohm ## Footnote The symbol for ohm is Ω.

Question 35

What happens to the current when the resistance of component C is decreased?

Answer 35

Increases ## Footnote This is due to Ohm's Law.

Question 36

Complete the equation connecting current, potential difference and resistance: Current = _______ / Resistance.

Answer 36

Potential difference

Question 37

What is the potential difference across a 9 ohm resistor when the current through it is 3 A?

Answer 37

27 V ## Footnote Using the formula V = I × R, where I is current and R is resistance.

Question 38

Calculate the resistance when the potential difference is 100 V and the current is 4 A.

Answer 38

25 ohms ## Footnote Resistance can be calculated using R = V / I.

Question 39

What is the total resistance of a 200 ohm and 180 ohm resistor connected in series?

Answer 39

380 ohms

Question 40

What is the total resistance of a 500 ohm and 1.5 k ohm resistor connected in series?

Answer 40

2000 ohms

Question 41

If resistors are added to a circuit in series, the total resistance _______.

Answer 41

Increases

Question 42

If resistors are added to a circuit in parallel, the total resistance _______.

Answer 42

Decreases

Question 43

What two measurements must a student make to calculate the resistance of a resistor?

Answer 43

Potential difference and current

Question 44

Describe how a student can increase the current through the resistor using the same circuit.

Answer 44

Increase the voltage of the power supply

Question 45

True or False: The total resistance stays the same when resistors are added in series.

Answer 45

False

Question 46

True or False: The total resistance decreases when resistors are added in parallel.

Answer 46

True

Question 47

What is resistance

Answer 47

Electric wires are made of metal, which have electrical resistance. The atoms in a solid metal are arranged in a regular lattice structure. The outer electrons from each atom are free to move through the structure, forming a current. However, they may collide with atoms or meet defects in the lattice. This reduces the number of electrons flowing, which reduces the current. Conductors have a low resistance and insulators have a high resistance.

Question 48

What is resistance a measure of?

Answer 48

Resistance is a measure of the difficulty of passing an electric current through a conductor

Question 49

Is a longer thinner wire or a shorter fatter wire have more resistance?

Answer 49

Longe thinner wire has more resistance This is because electrons bump into positive metal ions as they travel through the wire and the longer the wire the more ions there are to bump into.

Question 50

What is resistance measured in

Answer 50

Ohms

Question 51

What is potential difference measured in

Answer 51

Volts

Question 52

What equation equals resistance

Answer 52

Resistance = potential difference / current

Question 53

What is the symbol for current

Answer 53

I

Question 54

What is the symbolism for potential difference

Answer 54

V

Question 55

What is the symbol for resistance

Answer 55

R

Question 56

How is a voltmeter or an ammeter connected in a circuit

Answer 56

Voltmeter in parallel Ammeter in series

Question 57

What pushes the electrons round the circuit

Answer 57

Power supply

Question 58

What does the ammeter measure

Answer 58

Current

Question 59

A current of 2.0 A flows through a component with a potential difference of 12 V. Calculate the resistance of the component.

Answer 59

Rearrange the equation to find resistance and then substitute in the known values. potential difference = current × resistance Resistance = 12/2.0 =6 ohms

Question 60

How much power is transmitted by a current of 2.0 A flowing at a potential difference of 5.0 V?

Answer 60

10W

Question 61

What current flows in a 100 Ω resistor with a potential difference of 5 V across it?

Answer 61

0.05A

Question 62

How much power is transmitted by a current of 2.0 A flowing through a 6.0 Ω resistor?

Answer 62

24W

Question 63

What is the equation for power

Answer 63

Resistance x current squared

Question 64

What are the mistakes?

Answer 64

A = cells facing the wrong way B = plus and minus on wrong side C = the amps should be the same on both sides D = The switch is open

Question 65

What is a variable resistor vs a resistor and how does a variable resistor work?

Answer 65

Resistors are electronic components used in circuits. Resistors control current. A variable resistor allows the amount of resistance in a serial circuit to be changed. It is made up of a coil of wire and a slider that touches the wire The resistance changes when the slider moves along the coil.

Question 66

Learn this how many did you know?

Question 67

In a seriese circuit is the current the same everywhere or different?

Answer 67

Same

Question 68

Why in a seriese circuit is will it get dimmer when mor bulbs are added?

Answer 68

Because it is harder for the electricity to get through. The resistance of the circuit is higher if more bulbs are added

Question 69

What goes here

Answer 69

0.5A

Question 70

What goes here

Answer 70

Top = 1A Bottom = 0.5

Question 71