Current and Voltage, Series and Parallel Having measured the current and voltage in series and parallel circuits, I can design a circuit and show the advantages of parallel circuits in everyday application- SCN 3-09a.

Today we are going to … Learn what the terms ‘current’, ‘voltage’ and ‘power’ represent Learn about the differences between series and parallel circuits And we will… Be able to build series and parallel circuits Be able to measure current and voltage in series and parallel circuits.

Let’s look at electrical charge a bit more… We know that electricity is a form of energy that helps make lots of useful things work. Electrical current is the term we use to describe the movement of electrical charge throughout a circuit. I look scary, but I’m not!

Charge is a feature of matter. It causes a force (a push or pull) when placed near another charge. Charges can be positive or negative. Like charges repel each other. Opposite charges attract each other.

If an object loses electrons it becomes positively charged If an object gains electrons it becomes negatively charged

Electrical current (I) is defined as how much charge (Q) is transferred per second (s) -The more charge that flows, the bigger the current- Current = Charge/time Q I t - Current is measured in Amperes (A) - Time is measured in seconds (s) - Charge is measured in Coulombs (C)

A potential difference is needed to allow an electrical charge to flow through a component. This difference in electrical energy between two parts of a circuit is called the voltage. Voltage is measured in… Volts! (V)

Series Circuits When components are connected one after the other in a continuous loop, we say the circuit is arranged in series (it has no branches…) Just like this! Try experimenting with this now! What happens when you unplug one bulb?

Parallel Circuits When components are connected on different loops, we say the circuit is arranged in parallel (This variety of circuit has branches…) Like this one! Try experimenting with this now! What happens when you unplug one bulb?

Measuring the Current in a Series Circuit AA We measure current using an Ammeter.

We connect an ammeter in series with the components The current is the same everywhere in the series circuit. I1 = I2 AA I1 I2 Try experimenting with this now! Your total current is determined by the number of cells.

We connect a voltmeter in parallel with the components V The voltage is shared between all of the components in the circuit. Try experimenting with this now!

In a parallel circuit, the total current is distributed across the components. I1 and I5 are 0.3A I2 = 01.A I3 = 0.1A I4 = 0.1A A A A A A I1 I2 I3 I4 I5

V1 V3 V2 V V V In a parallel circuit, the voltage measured across is each component is the same as the voltage of the source. V1 = 1.5V V2= 1.5V V3= 1.5V

What about POWER? Power (P) is a measure of the rate of energy transfer. Power is measured in Watts (W) P I V

Today we have… Learnt what electrical current is and how charges behave Learnt the relationship between current, charge and time. Learnt what voltage is Learnt how to measure voltage and current in series and parallel circuits Learnt what power is Learnt how to calculate Power when we know the current and the voltage