Download Quiz 3

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1. What is the current flowing in a
circuit if 30C are passed in 1
minute?
answer
Q = It
30 = I x 60
I = 30/60
0.5A
2. What voltage would be measured
over a 100 Ω resistor when 10mA
flows through it?
answer
V
= IR
V = 0.01 x 100
1V
3.
How many joules of energy are
transferred by a 60W bulb every
second?
answer
P = E/t
60 = E/1
E =60/1
60J
4. Calculate the size of the current flowing
in a 3kW mains operated appliance.
answer
13A
5. A television draws 0.1 A and has a
resistance of 5000Ω. Calculate the
power consumption
answer
P = IV
P = 0.1 x 5000
50W
6. How many 1.5V bulbs operating at
their correct voltage could be connected
in series with a 6V cell?
answer
Vs = V1+ V2…
6 = 1.5 +1.5 + 1.5 +1.5
6 = 4(1.5)
Four bulbs
7.
What is the total resistance of a set
of Christmas lights comprising of 30
individual 10Ω lamps in series?
answer
Rt = R1+R2+…
Rt= 30(10)
3600 Ω or 3.6kΩ
8.
An electrical supply for a caravan
delivers a total current of 2A to the fridge
and lighting circuits. If the lights use
0.25A, what is the operating current of the
fridge?
It answer
= Ilights+Ifridge
2= 0.25 + Ifridge
I
fridge
= 2 - 0.25
1.75A
9.What is the total resistance of
three 90Ω resistors connected in
parallel?
answer
1/Rt = 1/R1+1/R2+1/R3
1/Rt = 1/90+1/90+1/90
1/Rt = 3/90
Rt = 90/3
30 Ω
10. Work out the enegy used in
kWhr for a 2000 W electric
heater which is used for 45
mins?
answer
E = Pt
E= 2(kW)x 0.75(hr)
1.5kWhr
11. How many joules are used if a
tumble dryer uses 0.75 kWh?
answer
750Whr
750J/s(hr)
750x3600
2700kJ or 2700000J
12.
Select the appropriate formula from your data book..
That shows the relationship between charge, current
and time.
answer
Q=It
13.
Select the appropriate formula from your data book..
That shows the relationship between voltage, current
and resistance.
answer
V = IR
14. State Ohm’s Law.
answer
V = IR
15.
Select the appropriate formula from your data book..
To calculate resistances in series.
answer
Rt = R1+R2+R3
16.
Select the appropriate formula from your data book..
For combining resistors in parallel.
answer
1/Rt= 1/R1 +1/R2 + 1/R3
17.
State the relationship between
Energy and Power
answer
P = E/t