Know it! 2

Question 1

Write down equation to show the relationship between current, charge and time

Answer 1

charge = current x time
Q = I x t

Question 2

State the difference between alternating current (a.c.) and direct current (d.c.)

Answer 2

• Direct current flows in one continuous direction
• Alternating current reverses direction, periodically

Question 3

Write down the equation to show the relationship between energy transferred, charge and voltage.

Answer 3

energy transferred = charge x voltage
E = Q x V

Question 4

Write down the equation to show the relationship between power, current and voltage.

Answer 4

power = current x voltage
P = I x V

Question 5

Write down the equation to show the relationship between energy transferred, current and voltage, and time

Answer 5

energy transferred = current x voltage x time
E = I x V x t

Question 6

Write down the equation to show the relationship between resistance, voltage and current.

Answer 6

voltage = current x resistance
V = I x R

Question 7

Write down the equation for transformers to show the relationship between input turns and output turns, and input voltage and output voltage

Answer 7

input (primary) voltage/output (secondary) voltage = primary turns/secondary turns

Question 8

Write down the equation for transformers to show the relationship between input voltage and output voltage, and input current and output current, when the transformer is 100% efficient

Answer 8

V (tiny p) I (tiny p) = V (tiny s) I (tiny s)

Question 9

Write down the equation to show the relationship between the speed of a wave, its frequency and its wavelength

Answer 9

wave speed = frequency x wavelength

Question 10

frequency and time period of a wave

Answer 10

frequency = 1/time period

Question 11

refractive index of a material and the angle of incidence and the angle of refraction of light passing into it

Answer 11

n = sin i/sin r

Question 12

critical angle and the refractive index of a material

Answer 12

sin c = 1/n

Question 13

the specific heat capacity of a substance, the change in thermal energy, change in temperature and the mass of the substance

Answer 13

change in thermal energy = mass x specific heat capacity x change in temperature

Question 14

gas law equations shows relationship between pressure and volume of a gas in two different situations

Answer 14

p1V1 = p2V2

Question 15

gas law equations shows relationship between pressure and temperature of a gas in two different situations

Answer 15

p1/T1 = p2/T2

Question 16

orbital speed of an object, in terms of the orbital radius and the time period

Answer 16

orbital speed = 2 x π x orbital radius/time period

Question 17

unit for mass

Answer 17

kilogram (kg)

Question 18

unit for distance

Answer 18

metre (m)