Flashcards in Electrical Energy And Power Deck (11)
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1
Q
What is Power?
A
Is the rate of doing work
2
Q
What is Power measured in?
A
Watts (W)
3
Q
What is the Power equation?
A
P = E/t
4
Q
In a electrical circuit what is E that is part of P = E/t?
A
Work done moving a charge
5
Q
What is the Power equation for electrical circuits?
A
P = IV
6
Q
Why does the Power = IV equation make sense?
A
- Potential Difference is defined as the work done per coulomb
- Current is defined as the number of Coulombs transferred per second
- So P.D x Current is work done per second, i.e Power
7
Q
Combining P = IV and V = IR together can give you more equations such as?
A
P = I*2 x R
P = V*2 / R
8
Q
Energy is easy to calculate if you know the […….]
A
Power
9
Q
If you want to work out total energy transferred what is the equation we use?
A
E = Pt
10
Q
By substituting in other equations what can E =Pt be?
A
W = IVt Or W = (V*2 / R)t Or W = I*2 x R x t
11
Q
How do you investigate the power output of an electric motor?
A
- Attach mass to the motor as shown and connect the motor to the circuit as shown
- Record the time taken for the motor to raise the mass a set distance (using a stopwatch and meter rule)
- Calculate the work done against gravity using ΔEgrav = mg Δh
- Calculate the Power output of the motor using P = W/t
- Can also investigate efficiently taking P.D reading and Current readings to calculate the Power using P = IV
- Use the equation Efficiency equation Efficiency = (useful power output / Total power input)
- Could also investigate, using this apparatus, to investigate wether the power input and power output of the motor varies with the laid attached to it by varying the mass.
