Archive for the ‘Physics’ Category

Capacitors

Posted: February 13, 2014 in Physics

A capacitor is a component that stores energy in it. It has two plates with a dielectric material in between. The greater the energy stored, the greater the capacitance. The greater the area of the capacitor plates, the greater the capacitance and the lesser the distance between the plates, the greater the capacitance. Apart from its dependence on its plate distance and area, capacitance is also dependent on the type of dielectric material it is made of.
Some examples of dielectric material are sand, glass, plastic etc.

Capacitors are widely used. Some examples include alarm clock, XRAY machines, calculators and hybrid cars etc.

Technically, capacitors store charge. They can be easily charged by a battery. This stored energy can be to put to use in many ways, for example, in lighting up a bulb. But one thing to keep in mind is that a capacitor loses its charge rather quickly, unlike a battery. So, a bulb would go off or become dim once the capacitor has been completely discharged. And this would happen rather quickly.

Once a capacitor has fully charged, a DC current cannot flow through it. However, an alternating current can always flow through it.

Mathematically, capacitance is found by the formula C=Q/V where Q is the charge and V is the voltage.

The capacitors can be placed in series and in parallel just like the resistors. However, the calculation is opposite to that of the resistors. When capacitors are in parallel, their capacitance is just added. When in series, the inverse of each capacitor is added and the total is inversed.

Just for entertainment, here is the link to a post: http://www.instructables.com/id/Make-A-Water-Bottle-Capacitor/?ALLSTEPS. This person actually puts the extra water bottles to good use by turning them into a capacitor. This is just for entertainment purposes. Try at your own risk if you are really interested.

Equilibrium in everyday life

Posted: March 1, 2011 in Physics

The Wikipedia defines equilibrium as the condition of a system in which competing influences are balanced. This particular word is used extensively in the realms of physics as well as biology, chemistry and economics etc. In whatever context it is used, it almost always refers to balance. This phenomenon helps us in carrying out our daily routines in one way or other. However, we tend to overlook these situations and continue with our daily lives. Today, I am going to enumerate as well as briefly explain some of the examples from our daily lives which describe the concept of equilibrium.

Let us start with a toaster. You plug it into a socket and switch it on. The electric current will flow from the socket and into the appliance. With the increase in electric current, the filaments inside the toaster will start to glow. At a point, the amount of electric current flowing to the toaster will become equal to the heat energy produced by the toaster. Then we would be able to say that the toaster has achieved a state of equilibrium. In simpler words, a balance would be created between the electrical energy and the heat energy.

When a pendulum is made to stop and hanged loosely downwards, it is said to be in the equilibrium position.

Let us look at a simple example of a see-saw. If two individuals, having almost identical weights, sit on opposite sides of the see-saw and also make sure that their distances from the fulcrum are same, then the see-saw would not be tilted. It would be stationary and straight.csaw1 This would be the point of equilibrium or balance of the see-saw. The balance would not be disturbed until another individual joins them or one of them changes their distance from the fulcrum point.csaw2 Now, let us suppose that on one side of the see-saw, two individuals are sitting together. The balance would be disturbed and it would tilt. To again move it into a state of equilibrium, the individual sitting alone would have to increase the distance from the fulcrum until they get balanced again.

Have you ever played tug of war? Has a situation arisen when your team and the opposing team are pulling the rope with full power and vigour, yet the rope is not moving in either of the directions? This state is actually another example of equilibrium. This would normally occur when the team members of both the teams are applying equal strength or in technical terms, force. Bring another guy in any one of the team and see for yourself how the state of equilibrium is broken.tug of war I came across a picture on the net of a boy balancing a bamboo stick with his right and middle fingers at the middle of the stick. The point worth telling is that a pair of scissors and a thermos was also placed on the stick and still it was in an equilibrium position. The pair of scissors was placed at the end of the stick while the thermos was positioned very near his fingers. Then how was the stick balanced?bamboobalance This occurred because the moment of force on one side was equal to the moment of force on the opposite side. Moment of force is determined by finding out the product between the weight of the object (in this case the pair of scissors or the thermos) and the distance between the point of balance (the fingers). Less weight but larger distance of the scissors and lesser distance but larger weight of the thermos accounted for the moment of force of both to become equal, which resulted in an equilibrium state.

A fish is an ideal example of equilibrium. A fish swimming at a certain depth under the sea without floating upward or sinking unexpectedly is said to be in equilibrium. This is achieved by the swim bladder present in it. The bladder is present in the belly of a fish. It is like a sac. Its function is to contract or expand according to the depth of the fish, thus allowing it to remain at a specific depth.

In economics, the concept of demand and supply is a really important one. Demand refers to the amount of a product consumers want to buy whereas supply is known by the quantity of a product available in a market. Less demand and greater supply causes the price of a product to decrease. On the other hand, greater demand and less supply results in higher price of the product. However, on occasions when the demand of a product or a service is equal to its supply, the economy of that product is said to be in equilibrium.

So, these were few of the examples of equilibrium occurring in our daily lives. The examples of equilibrium are present in front of us. All we need is a little bit of observational and analytical skills to figure out how we can apply the concepts of equilibrium in our day-to-day activities.