Gr9 Physics Review

Question 1

Explain the electrical laws

Answer 1

Like charges will repel
Opposite charges attract
Neutral are attracted to a charge and attract a charged

Question 2

Explain charging by conduction

Answer 2

Conduction means it comes in contact

• neutral object gains same charge as object touching it

Question 3

Explain charging by induction

Answer 3

-nearby objects can induce charge
-nearby charged has opposite charge (opp attract)

Question 4

Explain charging by friction

Answer 4

Similar to contact but rubbing two objects can cause one to gain and one object to lose.

Question 5

Grounding

Answer 5

path for excess electrons to/from the Earth.

Question 6

Series circuit

Answer 6

one path

Question 7

Parallel circuit

Answer 7

more then 1 path

Question 8

voltmeters and ammeters

Answer 8

voltmeters are a box around the lightbulb with a V in the circle

Ammeters are a circle with an A on the circuit.

Question 9

How to find the voltage, current and resistance formulas

Answer 9

V=I x R
I=V/R
R=V/I

Question 10

What is static

Answer 10

Electron affinity is the tendancy of a substance to hold onto this particle.

Question 11

What are electrochemical cells

Answer 11

package of chemicals (electrode and electrolytes). Electrolyte is liquid or paste and electrode is a metal strip that reacts with the electrolyte.

Question 12

Voltage formulas (series and parallel)

Answer 12

Series:
VT=V1+V2=V3

Parallel:
VT= V1=V2=V3

Question 13

Current formulas (series and parallel)

Answer 13

Series:
IT=I1=I2=I3

Parallel:
IT=I1+I2+I3

Question 14

Resistance formulas (series and parallel)

Answer 14

Series:
RT=R1+R2+R3

Parallel
1/RT= 1/R1+1/R2+1/R3

Question 15

Factors affecting resistance

Answer 15

1. Material - copper=higher then silver
2. Temperature - hotter=higher, colder=lower
3. Length= longer=higher, thinner=lower
4. Cross-sectional area= Thinner=higher, Fatter=lower

Question 16

What is the energy formula

Answer 16

E= v x I x t

Energy in J
Voltage in V
Current in A
Time in seconds

Question 17

What is the power formula

Answer 17

P= e / t

Power is in W
Energy is in J
Time is in seconds

Question 18

What are the energy efficiency formulas

Answer 18

OE/IE x 100% = %effi

OE= input x eff

IE = out x eff

Question 19

What is the cost formula

Answer 19

C=P x T x Rate

Cost is in $
Power in kw
Time is in hours
Rate is in kwh
(rate is found in graph given and you put a 0. in front)

Question 20

On a battery which side is positive and negative

Answer 20

electrons move from the black side which is negative to the positive side which is red.

Question 21

What happens to the rest of the energy when energy is converted and used (if used in a machine ex blender)

Answer 21

Kinetic energy was converted to other types of energy. So the rest of the energy can be converted to heat or light.