Capacitors

Capacitors are devices used to store electric charge and usually involve conducting plates separated by an insulator. (One plate is positive while the other is negative.)

When the capacitor is connected to a battery, electrons flow from the negative terminal to plate


Capacitors are widely used in electronic circuits to block the flow of direct current (D.C) while allowing alternating current(A.C) to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes.

SPM past year questions:
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related video from http://ec.europa.eu/research/mariecurieactions/

Nuclear Fission

1. What is atomic mass unit (a.m.u)?


The symbol for the atomic mass unit is u.

1 u is defined as 1/12 x ( mass of the carbon-12 atom)

1 u = 1,66 x 10 ^-27 kg.

2. Describe nuclear fission.



A nuclear fission is a nuclear reaction in which a heavy nucleus splits into split into two or more lighter nuclei which the release of energy.

The nucleon number and proton number must be balanced in the nuclear equation.

3. Describe chain reactions.



A chain reaction is a process in which at least one neutron produced in a fission induces a second fission.
A neutron produced in the second fission induces a third fission, and the process is repeated.