Ohm's law and Kirchhoff's law

In class today, we learned about Ohm's law, which states that current and voltage are directly proportional to each other. In other words, when current goes up, voltage goes up, and when current goes down, voltage goes down. Also, Ohm's law states that current and resistance are inversely proportional with each other, in other words, when current goes up, resistance goes down, and when current goes down, resistance goes up.

Gustav Robert Kirchhoff was a scientist in the 17th century whose research lead to his proposal of his laws of current and voltage.

Firstly, Kirchhoff's current law states that the total amount of current into a junction point (a point where two or more things join together) equals the total current that flows out of that same junction.

Secondly, Kirchhoff's voltage law states that the total amount of voltage that decreases in any complete circuit loop always equals the total amount of voltage gained in that circuit loop.

Notice how in the first law, the currents from all four sources going into the junction point (a-d) is equal to the current flowing out to the two sinks (e-f)

In the second law, the voltage source, a, is where the voltage comes from, where the current "recharges" its voltage. This increase is equal to all decreases in voltage throughout the complete circuit (b-f).

Ohm's Law can be demonstrated with the triangle shown below.

Batteries to Circuits

A battery has both a positive side and a negative side. When one observes the transition of energy starting from the negative side to the positive side, this is called electron flow. When one observes the transition of energy from the positive side to the negative side, this is called electrical current.

In a nutshell, the chemical energy from the battery was converted into electrical energy, which was used to light up the lightbulb.


I'm terrible at paint. :(

Roller Coaster?!

Out of the dozens of roller coasters I've had the privilage to ride in my 16-year old lifespan, none has been more enjoyable than my rides on the Behemoth. The largest rollercoaster, (in terms of height) in the largest theme park in Canada, The Behemoth takes riders on for a full 3 minutes and 10 seconds of excitement and adrenaline. With a maximum height of 70 metres, and a length of over 1,600 metres, the Behemoth boasts the most noticable track in the park. What's more, the speed of The Behemoth can go up to 124 km/h, making it one of the fastest rides as well in Canada's Wonderland.


Some of the grueling twists & turns on the Behemoth



Riders on the Behemoth

The Behemoth track from afar

Energy Ball Exercise :)

On Friday, February 5, 2011, our physics class had the pleasure of taking part in the energy ball exercise. Mr. Chung had provided us with customized futuristic ping-pong balls that glowed and made sound through the use of electricity, and split us up into small groups of four to further experiment.

As our groups had soon realized, the ping-pong balls had small circuit boards inside, acting as the series circuit we'd learned. We'd discovered the trick of how to light the ball up: by forming a complete series circuit with our fingers. What's more, we were able to experiment different situations, such as conductivity of electricity on different materials, and under what circumstances a full circuit will not be formed. In the end, we'd come up with the conclusion that full circuits cannot be formed by two people who are not touching, or have some link or contact in between them.

To further test our class's concept, Mr.Chung assigned us the challenge of forming a human parallel circuit for two energy balls, with a switch to control one energy ball. This was done by forming an extra path for the electricity to flow through in the middle of the circuit, splitting up the two ping-pong balls.

My hypothesis for the fact that the energy ball works for some people, such as myself, and not for others, such as Mr. Chung, is that I was wearing shoes with rubber soles when I was touching the ball, hence acting as an insulator between me and the Earth/ground. Mr Chung, on the other hand, was wearing no shoes, or shoes made of material with a high conductivity, hence his electrical current through his body actually transferred to the ground, and thus his electricity level i his body was non-existant.

Simple Circuit

Parallel Circuit