Name: ______Group: ______Date: ______

Static electricity

1.Complete the following sentences, using the words or groups of words in the box below. You may use some words more than once.

•capture
•charge
•charging
•conduction
•contact
•Coulomb’s constant
•Coulomb’s law
•distance
•dynamic / •easily
•electrical force
•electrons
•friction
•heated
•immobile
•induction
•inversely
•metal-leaf electroscope / •negative charges
•neutral
•neutralize
•opposite signs
•positive charges
•proportional
•rest
•rubbed
•shared / •spark
•static
•surrounding air
•touched
•transfer
•without

a)After observing differences in the properties and behaviour of insulated charges
and charges in circuits, scientists distinguished two fields of study: ______electricity (or electrostatic electricity) and dynamic electricity. ______electricity deals with the movement of electrical charges.

b)Static electricity describes the phenomena related to electrical charges at ______. A ______can be used to detect the presence of static electricity in an object.

c)Electrically charged substances do not remain permanently charged. They lose their charge when they come in contact with water molecules in the ______. This loss explains why the effects of static electricity are less frequent during humid weather. In dry weather, static electricity can produce a small ______, indicating that bodies have lost their charges all at once in an electrical discharge. The air is ______by the electrons passing through it, and a flash of light is produced.

d)Matter can be charged by friction, ______or induction.

e)Charging by ______occurs when two bodies are rubbed against each other. The result is a ______of electrons from one body to
the other. Some substances, such as wool and glass, tend to give up electrons ______, while others, such as plastic and gold, tend to ______electrons. When a plastic rod is ______against a piece of wool, the ______from the wool move toward the plastic rod. By losing electrons, the wool will have a surplus of ______, and the plastic rod, by gaining electrons, will have a surplus of ______.

f)______byconduction occurs when a ______substance comes in contact with a substance that is already charged. The charges are then ______between the two substances, which now carry charges of the same sign. However, the resulting charge is weaker than the original one. This type of charging occurs when a metal-leaf electroscope is ______by a charged object.

g)Charging by ______occurs ______direct ______between the substances. When a charged substance approaches a neutral substance, the charges move to the neutral substance, creating an area with the opposite charge. If this neutral substance is insulated, the opposite charges will eventually ______each other as soon as the charged substance is removed.

h)According to ______, the electrical force between two ______and electrically charged particlesis directly ______to the product of their charges and ______proportional to the square of the distance between them.
It is expressed by the following equation:

Fe=whereFeis the ______in newtons (N)

k is______, or 9  109

q1 is the ______of the firstparticle in coulombs (C)

q2 is the ______of the second particle in coulombs (C)

r is the ______between the two particles in metres (m)

2.In each of the following situations, has the object been charged by friction, conduction or induction?

a)To make a balloon stick to the wall, you rub it on your head.

b)A trickle of water is redirected by a charged ruler.

c)Clothes are full of static electricity when they come out of the dryer.

d)A teenage boy becomes electrically charged by dragging his feet.

e)You put a charged object in contact with a metal-leaf electroscope.

f)Confetti is drawn to charged objects.

3. Using the equation for Coulomb’s law, isolate the variable to find:

a)the charge of the first particle

b)the distance between the two particles

4.Calculate the magnitude of the electrical force if the charge of the first substance is
6  10-10C and the charge of the second substance is 4  10-8C. The substances
are placed 2.5cm apart.

5.What is the distance between two particles when the first, with a charge of 6  10-6C,
exerts an electrical force of 0.312N on the second, with a charge of 8  10-8C?

1

Activity 20

Support activities – Second Year of Secondary Cycle TwoStatic electricity