4.3 Electrical Circuits Flashcards Preview

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Flashcards in 4.3 Electrical Circuits Deck (12)
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1
Q

What is Kirchhoff’s first law?

A

The sum of currents entering a junction (or node) in a circuit is equal to the sum of the currents leaving the junction

2
Q

What is Kirchhoff’s second law?

A

In any closed loop, the sum of the emf is equal to the sum of the products of the current and resistance.

3
Q

What is the potential divider equation?

A

Vout= Vin x R2/(R1+R2)

4
Q

What are the variations on a potential divider circuit?

A

Variable resistor
Thermistor
LDR

5
Q

What is a potential divider circuit?

A

It uses two resistors in series to split or divide the voltage of the supply in a chosen ratio so that a chosen voltage can be provided to another device or circuit.

6
Q

What is terminal pd?

A

The potential difference recorded across the terminals of a cell.

7
Q

What are lost volts?

A

The difference between the emf and the terminal pd when charge flows

8
Q

what is internal resistance?

A

The resistance to electric current of the materials inside a source. When current flows, energy is transferred to these materials, resulting a drop in the terminal pd.

9
Q

Equation for emf with r

A

e = I(R+r)

10
Q

Define kilowatt hour

A

Energy transformed by a device working at 1kW for 1h

11
Q

Explain why Resistivity rather than resistance of a material is given in tables of properties of materials.

A

p is independent of dimensions of the specimen of the material.

12
Q

Why is it not advisable to maintain high currents for a long time?

A

Excessive heating of CELL/ energy wasted INTERNALLY