Flashcards in 4.3 Electrical Circuits Deck (12)

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1

## What is Kirchhoff's first law?

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

2

## What is Kirchhoff's second law?

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

3

## What is the potential divider equation?

### Vout= Vin x R2/(R1+R2)

4

## What are the variations on a potential divider circuit?

###
Variable resistor

Thermistor

LDR

5

## What is a potential divider circuit?

### 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

## What is terminal pd?

### The potential difference recorded across the terminals of a cell.

7

## What are lost volts?

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

8

## what is internal resistance?

### 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

## Equation for emf with r

### e = I(R+r)

10

## Define kilowatt hour

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

11

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

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

12