An ohmic conductor follows Ohm’s Law, meaning its resistance remains constant regardless of voltage or current changes. Materials like copper, aluminum, and silver are considered ohmic conductors because they exhibit this linear relationship.
Which of the following is an example of a non-ohmic conductor?
A Diode
B Resistor
C Aluminum wire
D Copper wire
A diode is a non-ohmic conductor because its resistance varies with the applied voltage, and it allows current to flow in only one direction. Unlike ohmic conductors, its current-voltage relationship is nonlinear.
What is the main effect of increasing the electric current in a conductor?
A Increased power factor
B Increased resistance
C Increased temperature
D Decreased voltage
When electric current passes through a conductor, the conductor’s temperature increases due to the collisions between electrons and atoms, which is a direct consequence of Joule heating. This heat generation increases with the current.
Which of the following is commonly used to limit the current in a circuit?
A Transformer
B Capacitor
C Inductor
D Resistor
A resistor is used to limit the current in a circuit by offering resistance to the flow of electrons. It is a simple and effective way to control the current, ensuring the safe operation of the circuit.
What is the relationship between the current and voltage in a non-ohmic conductor?
A Constant
B Nonlinear
C Directly proportional
D Inversely proportional
In a non-ohmic conductor, the relationship between current and voltage is nonlinear. This means the resistance changes with voltage, as seen in devices like diodes, which have varying resistance based on the applied voltage.
Which of the following materials has the highest electrical conductivity?
A Silver
B Iron
C Aluminum
D Copper
Silver has the highest electrical conductivity of all metals, followed by copper. It allows electricity to pass through it with minimal resistance, making it ideal for specialized electrical applications, though copper is more commonly used due to cost.
What is the primary cause of an electric shock?
A High voltage
B Low resistance
C Current flow through the body
D High current
An electric shock occurs when current flows through the body, potentially causing harm or injury. The severity of the shock depends on the amount of current, the path it takes, and the duration of contact.
What is the primary effect of a short circuit?
A Fuse melts
B Current flow increases
C Voltage increases
D Current flow stops
In a short circuit, the current increases significantly due to the low resistance path created between two conductors. This can cause excessive heating and potentially lead to damage or fires unless protected by fuses or circuit breakers.
Which safety device is designed to protect against electrical overloads?
A Inductor
B Capacitor
C Fuse
D Transformer
A fuse is designed to protect against electrical overloads by interrupting the current when it exceeds a safe level. The wire inside the fuse melts when the current is too high, preventing damage to electrical components.
What does the thermal effect of electricity describe?
A Conversion of energy to heat
B Energy stored in an inductor
C Energy stored in a capacitor
D Conversion of current to voltage
The thermal effect of electricity describes the generation of heat when electric current passes through a conductor. This is due to the collisions between electrons and atoms in the conductor, known as Joule heating.
Which of the following devices uses electromagnetism to convert electrical energy into mechanical energy?
A Transformer
B Electric motor
C Battery
D Capacitor
An electric motor uses electromagnetism to convert electrical energy into mechanical energy. When a current flows through a coil in a magnetic field, it experiences a force that causes the motor to rotate and do mechanical work.
What does the symbol of a light bulb represent in a circuit diagram?
A A resistor
B A power source
C A switch
D A light-emitting component
The symbol of a light bulb in a circuit diagram represents a light-emitting component. The bulb glows when current flows through it, converting electrical energy into light energy, commonly used for illumination.
What is the primary function of a transformer in electrical systems?
A Store electrical energy
B Change frequency
C Change voltage levels
D Convert DC to AC
A transformer is used to change voltage levels in an AC circuit. It can either step up or step down the voltage using electromagnetic induction, making it an essential component in power transmission systems.
In a series circuit, what happens if one component fails?
A Entire circuit stops
B Voltage increases
C Current continues
D Current increases
In a series circuit, if one component fails, the entire circuit stops because the current has only one path to flow. A break anywhere in the circuit will prevent current from reaching other components.
Which of the following is true for a parallel circuit?
A Components are connected end-to-end
B Voltage is the same across all components
C The current decreases
D Current remains the same
In a parallel circuit, the voltage across all components remains the same. Each component receives the same voltage as the power source, and the total current is the sum of the currents through the individual components.