Year 12 A’ level physics Taster Day
Algebra
At A’ level physics you need to be able to rearrange equations. Try the following
examples where you have to rearrange the equation to make the symbol in brackets
the subject. You will come across all these equations in A’ level physics
1. V = IR
(R)
2. v= s/t
(t)
3. P=F/A
(A)
4. P1V1 = P2V2
(V2)
2
5. KE = ½ mv
(v)
2
6. P = I R
(I)
7. GPE = mgh
(h)
8. v = u +at
(t)
2
2
9. v = u +2as
(a)
10. E = V +Ir
(r)
11. F = 6πηrv
(η)
12. I = nqvA
(A)
2
13. mgh = ½ mv simplify and make v the subject
14. GmM/r2 = mv2/r simplify and make r the subject
Extension questions
1. E = IR +Ir
(I)
2. P1V1/T1 = P2V2/T2 (T2)
3. T = 2π√(x/g) (x)
4. n = sini /sinr ( r)
Converting Units
Milli: 1000mm = 1m
1mm = 1/1000 m
Kilo: 1kΩ = 1000Ω = 1x103Ω
1mA = 0.001A = 1x10-3A
Mega: 1MΩ = 1 000 000Ω = 1x106Ω
Micro: 1µA = 1/1000000 A = 1x10-6A
Convert the following into metres, amps, or ohms where relevant
1. 4mm
2. 250mm
3. 75mm
4. 0.5mm
5. 12mA
6. 0.6mA
7. 360mA
8. 0.05mA
9. 30kΩ
10. 0.8kΩ
11. 9MΩ
12. 600MΩ
13. 0.05MΩ
14. 200µA
Extension Questions
1. A rectangular wire has dimensions 1.5cm and 4cm. Calculate its area in m2.
2. A resistor has an area of 12cm2. Convert this into an area in m2
3. A wire has radius 2mm. Calculate its area in m2 (A = πr2)
4. How many mm3 can you fit into 1m3?
5. The density of a substance can be calculated using density = mass/volume.
Calculate the density of a cube of side 2cm and mass 60g. Your answer
should be expressed in kg/m3.
6. Using resistance = voltage/current calculate the resistance of a component
that has current of 120µA when the p.d across it is 30kV
Standard form
Put the following into standard form
1. 20000V
2. 0.0036A
3. 0.000052m
4. 7200000W
5. 400kW expressed as watts
6. 7mA expressed as amps
7. 25x107J
8. 600x10-9m
9. 0.04x10-3A
10. Which of the following distances is greater; 400 x 10-7m, 3.5 x 10-6m
You will be tested on the following within the first two weeks of the start of the
autumn term so make sure that if you find these difficult you see one of your
physics teachers early in the autumn term to sort it out
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Rearranging equations
Conversion of units including milli, micro, kilo and mega
Conversion of area from mm2 and cm2 to m2
Conversion of volume from mm3 and cm3 to m3
Use of standard form