Electricity I - SS3 Physics Past Questions and Answers - page 2
Which of the following materials is a good electrical insulator?
copper
aluminium
rubber
silver
An electric field is defined as:
a region in space where a magnetic force is exerted
a region in space where an electric force is exerted
a region in space where the speed of light is different
a region in space where gravity is stronger
Explain the concept of electric charge
Electric charge is a fundamental property of matter, which arises due to the presence or absence of electrons in an atom or molecule. Electrons have a negative charge, and protons have a positive charge, whereas neutrons have no charge. The unit of electric charge is Coulomb (C). Electric charges are responsible for the creation of electric fields, which are regions in space where electric charges experience a force. The strength of an electric field is directly proportional to the charge and inversely proportional to the distance between the charges.
What are the properties of electric charge?
The electric charge has two fundamental properties, which are as follows:
1. Like charges repel each other, whereas unlike charges attract each other.
2. Electric charge is conserved, which means that it cannot be created or destroyed but can be transferred from one object to another.
What is Ohm's law?
The current through a conductor between two points is directly proportional to the voltage across the two points
The resistance of a conductor is directly proportional to the current flowing through it
The resistance of a conductor is directly proportional to the voltage across it
The voltage across a conductor between two points is directly proportional to the resistance of the conductor
Which of the following is a unit of resistance?
Ohm
Watt
Volt
Ampere
What happens to the current in a circuit if the resistance is increased while the voltage remains constant?
The current increases
The current decreases
The current remains the same
The current becomes zero
A resistor has a resistance of 100 ohms. If a voltage of 10 volts is applied across it, what is the current through the resistor?
0.1 A
1 A
10 A
100 A
Which of the following materials has the highest electrical resistance?
Copper
Aluminum
Silver
Glass
What is Ohm's law?
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature and other physical conditions remain constant.