Electricity

Question 1

Ohms law

Answer 1

V = IR

Question 2

Voltage unit

Answer 2

Volt (Joules divided by coulomb)

Question 3

Current unit

Answer 3

Coulomb (Coulombs per seconds)

Question 4

Resistance formula

Answer 4

Resistance equals to voltage divided by current

Question 5

Power formula

Answer 5

Power is voltage into current

Question 6

Power unit

Answer 6

Joules per coulomb (Watt)

Question 7

Energy equals to power times time, therefore __________

Answer 7

E = current x voltage x time

Question 8

Coulomb’s law

Answer 8

Question 9

Resistance formula

Answer 9

Question 10

What does this symbol represent?

Answer 10

Resistor

Question 11

What does this symbol represent?

Answer 11

Resistor

Question 12

What does this symbol represent?

Answer 12

Resistor

Question 13

What does this represent?

Answer 13

Battery
(The bigger line is positive, and the smaller line is negative)
Current flows from positive to negative

Question 14

What does this symbol represent?

Answer 14

Voltmeter

Question 15

What does this symbol represent?

Answer 15

Ammeter

Question 16

Series circuit

Answer 16

Current constant

Question 17

Kirchhoff’s laws

Answer 17

First law: total current entering a junction = total current leaving the junction
Second law: the directed sum of the potential difference around any closed loop is zero.

Question 18

Parallel circuits

Answer 18

Voltage is constant

Question 19

Capacitance unit

Answer 19

Farad (Coulombs over volt)

Question 20

Capacitance formula

Answer 20

Question 21

Capacitence for series and parallel circuit

Answer 21

Series: 1/C = 1/C1 + 1/C2 + 1/C3 + …
Parallel: C = C1 + C2+ C3+ …

Question 22

Energy discharged by a capacitor formula

Answer 22

Question 23

Electric field strength formula

Answer 23

Question 24

True or false: electric field is a vector

Answer 24

True

Question 25

Coulomb’s constant

Answer 25

9 x 10^9 Nm^2/C^2

Question 26

Electric field intensity, voltage, and distance formula

Answer 26

Question 27

Ways of charging an object

Answer 27

1. Conduction 2. Induction 3. Friction 4. Grounding

Question 28

What is charging by conduction?

Answer 28

A charged object touches another object, and electrons move between them until they reach equilibrium (same potential). • Requirements: • Direct contact • Both materials must be conductors • An object must be charged • Result: The neutral object gains the same type of charge as the charged object.

Question 29

What is charging by induction?

Answer 29

A charged object is brought near (but doesn’t touch) a neutral conductor, inducing a separation of charges inside it. Then grounding is used to allow some charges to leave. • Requirements: • A charged object nearby (but no contact) • A neutral conductor • A path to ground (to allow electron flow) • Steps: 1. Bring charged object close → causes charge separation 2. Ground the conductor → lets opposite charges leave or enter 3. Remove the ground, then remove the charged object 4. The conductor is left with a net opposite charge • Result: The object is charged with the opposite type compared to the inducing object.

Question 30

What is charging by friction?

Answer 30

When two insulating materials are rubbed together, electrons are transferred from one to the other due to differences in their ability to attract electrons. • Requirements: • Two different insulating materials (e.g. rubber and wool) • Contact + rubbing (friction) • No grounding required • Result: One object becomes negatively charged (gains electrons), and the other becomes positively charged (loses electrons).

Question 31

Triboelectric series

Answer 31

The triboelectric series ranks materials based on their tendency to either donate or attract electrons.

Question 32

What is grounding?

Answer 32

Grounding is when a charged object is touch with the ground, and the ground either supplies or takes away electrons.