What is the main characteristic of an ohmic conductor?
A Variable resistance
B Zero resistance
C Constant resistance
D Infinite resistance
An ohmic conductor follows Ohm’s Law, which means its resistance remains constant regardless of the voltage or current. Materials like copper and aluminum are considered ohmic conductors because their resistance does not change with current or voltage.
Which of these is an example of a non-ohmic conductor?
A Gold wire
B Carbon filament
C Resistor
D Copper wire
A non-ohmic conductor does not follow Ohm’s Law, meaning its resistance changes with voltage or current. Carbon filament in light bulbs is a non-ohmic conductor, as its resistance increases with temperature.
What is the unit of electrical power?
A Watt
B Volt
C Ohm
D Ampere
Watt (W) is the unit of electrical power. Power is the rate at which electrical energy is used or converted. It is calculated as the product of voltage (V) and current (I), with the formula P=V×I.
Which of the following materials exhibits non-ohmic behavior?
A Silver
B Aluminum
C Copper
D Diode
A diode is a non-ohmic conductor. It does not follow Ohm’s Law because its current-voltage relationship is nonlinear. Diodes only allow current to flow in one direction and have varying resistance based on voltage polarity.
What effect does an increase in current have on the temperature of a conductor?
A Makes conductor colder
B Increases temperature
C No effect
D Decreases temperature
Thermal effects of electricity are caused by the flow of current through a conductor. As current increases, it causes the conductor’s atoms to vibrate more, generating heat. This phenomenon is known as Joule heating.
Which of the following materials is used to make resistors in circuits?
A Rubber
B Plastic
C Copper
D Carbon
Carbon is often used to make resistors. Its resistance can be precisely controlled, and it is a good choice for resistors in both low and high-power applications. The resistance of carbon is stable over a wide range of temperatures.
What is the primary cause of the thermal effect in electrical circuits?
A Voltage
B Electrical current
C Friction
D Magnetic fields
The primary cause of the thermal effect in electrical circuits is the electrical current. When current flows through a conductor, the resistance of the material causes energy to be dissipated as heat, increasing the temperature of the conductor.
What happens to a conductor’s resistance as its temperature increases?
A Resistance increases
B Resistance becomes zero
C No change in resistance
D Resistance decreases
For most conductors, as temperature increases, their resistance increases. This happens because the atoms in the conductor vibrate more, impeding the flow of electrons and making it harder for current to pass through.
What is the primary use of an ammeter in a circuit?
A Measure voltage
B Measure resistance
C Measure current
D Measure power
An ammeter is used to measure the current flowing through a circuit. It is connected in series with the circuit, and it measures the amount of electric charge passing through a point per unit of time (in amperes).
What does the symbol of a thermistor in a circuit represent?
A A battery
B A temperature-sensitive resistor
C A power source
D A switch
A thermistor is a type of resistor whose resistance changes significantly with temperature. It is used in circuits where temperature-sensitive control is required, such as temperature sensors and thermometers.
In which of the following is the thermal effect of electricity most useful?
A Electric bulb
B Transformer
C Electric fan
D Battery
The thermal effect of electricity is most useful in devices like electric bulbs, where electrical energy is converted into heat and light. The filament of the bulb heats up and emits light when current flows through it.
What happens to a non-ohmic conductor when the voltage is increased?
A Current decreases
B Resistance stays constant
C No change
D Resistance increases
Non-ohmic conductors, like diodes, exhibit a non-linear relationship between voltage and current. When voltage is increased, the resistance of a non-ohmic conductor usually increases, affecting the current flow in a way that does not follow Ohm’s Law.
Which material is typically used as an insulator in electrical wires?
A Aluminum
B Rubber
C Copper
D Silver
Rubber is commonly used as an insulator in electrical wires. It has high resistance and prevents electrical current from flowing outside the wire, ensuring safety and preventing accidental shocks.
What is the effect of a conductor’s length on its resistance?
A It depends on voltage
B Longer conductor decreases resistance
C Longer conductor increases resistance
D Length does not affect resistance
The resistance of a conductor is directly proportional to its length. The longer the conductor, the more the electrons collide with atoms, increasing the resistance and making it harder for current to flow.
Which of the following is true for a non-ohmic conductor?
A Its resistance varies with current
B It follows Ohm’s Law
C It has zero resistance
D Its resistance remains constant
A non-ohmic conductor does not follow Ohm’s Law. Its resistance changes with the applied current and voltage. Examples include diodes and filaments in light bulbs, where resistance varies depending on temperature and voltage.