PHY 10 - Electrical Circuits Flashcards Preview

GAMSAT March 2016 > PHY 10 - Electrical Circuits > Flashcards

Flashcards in PHY 10 - Electrical Circuits Deck (52)
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1

What is electrical current (I) ?

The amount of charge (Q) that flows past a point in a given amount of time (t)

 

2

What are the units of electrical current ? 

Amps (amperes)

OR
Coulombs/second 

3

How is an electrical current caused ? 

By the movement of electrons between two points of significant potential difference of an electrical circuit. 

4

How is energy lost by an electrical circuit ? 

Free electrons accelerate towards the positive connection. As they move, they collide with atoms in the substance, losing energy which we observe as heat. 

5

What is an electric current ? 

The motion of electrons 

6

What happens to an electrical circuit if the magnitude of the electric potential is increased ? 

The current will increase because the electrons will accelerate faster

7

Describe the concept of joule heating ? 

Collisions between electrons and atoms transfer energy to the atoms, which is released as heat. 

8

What are Ohmic conductors ? 

Materials such as joule heaters that obey Ohm's law, V=IR

9

What is Ohm's law ? 

10

Describe how Ohm's law works ? 

11

What is an Ammeter ? 

Used to measure the flow of current 

12

What is this ? 

An ammeter - measures the flow of current 

13

What is resistance (R) ? 

The measure of opposition to the flow of electrons in a substance 

14

What is resistivity (p) ? 

The inherent resistive property of a substance, which varies with temperature 

15

What is the equation that includes resistance and resistivity ? 

16

Why does electrical resistance vary with temperature ? 

The thermal motion of molecules increases with temperature, resulting in more collisions between electrons which impede their flow. 

17

What are the units of resistance ? 

Ohm's 

1 Ohm = 1 volt/ampere 

 

18

What happens when a positive current flows across a resistor ? 

There is a voltage decrease and a power loss. 

P = VI = V2/R

19

Describe how to calculate electrical power ? 

20

What does a resistor look like in a circuit diagram ?

21

What is this ? 

A bulb. 

 

(N.B. This also acts like a resistor!)

22

Why is a bulb in an electrical circuit treated like a resistor ? 

The filament inside a light bulb resists the flow of current, and becomes bright and hot. 

The brightness of the bulb depends on how much power it loses. 

23

What are the units of Q (charge) ? 

Coulombs (C)

24

What are Capacitors ? 

They are used in circuits to store charge, they are similar to batteries but can discharge much more quickly.

E.g. A flash gun on a camera

25

What is the unit of a capacitor ? 

Farad 

26

Describe what is meant by a series circuit ? 

One component follows another... 

27

How would you calculate the resistance of two resistors in series ? 

Rtotal = R1 + R2 etc... 

28

Describe what is meant by a parallel circuit ? 

29

How would you calculate the resistance of two resistors in parallel ? 

1/Rtotal = 1/R1 + 1/R2

30

What does EMF stand for ? 

Electromotive Force

E.g. A battery

Units: Volts 

Symbol: