Kerala SSLC · Physics · Class 10
Effects of Electric Current: Important Questions with Answers
These are 10 important multiple-choice questions from the Kerala SSLC Physics chapter “Effects of Electric Current” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.
Q1.Which of the following properties makes a fuse wire suitable for protecting electrical circuits?
- A)High melting point and high resistance
- B)Low melting point and low resistance
- C)Low melting point and high resistance
- D)High melting point and low resistance
Answer: C) Low melting point and high resistance
A fuse wire must have high resistance to generate sufficient heat quickly and a low melting point so it melts and breaks the circuit during overloading.
Q2.When an electric current flows through a solenoid, the magnetic field produced inside it resembles that of:
- A)A straight wire
- B)A circular loop
- C)A bar magnet
- D)A horseshoe magnet
Answer: C) A bar magnet
The magnetic field lines inside a current-carrying solenoid are parallel and uniform, creating a pattern identical to that of a bar magnet with distinct poles.
Q3.In Fleming’s Left Hand Rule, if the forefinger points towards the magnetic field and the middle finger indicates the direction of current, what does the thumb represent?
- A)Direction of induced current
- B)Direction of force/motion
- C)Polarity of the magnet
- D)Magnitude of voltage
Answer: B) Direction of force/motion
Fleming’s Left Hand Rule is used to find the direction of force on a current-carrying conductor placed in a magnetic field, where the thumb indicates the direction of motion or force.
Q4.Why are heating elements in appliances like electric irons typically made of Nichrome instead of Copper?
- A)Nichrome has lower resistivity than copper
- B)Nichrome has higher resistivity and does not oxidize easily
- C)Copper has a higher melting point than Nichrome
- D)Copper is cheaper than Nichrome
Answer: B) Nichrome has higher resistivity and does not oxidize easily
Nichrome has high resistivity which generates more heat for a given current, and it resists oxidation at high temperatures unlike copper which would melt or burn.
Q5.In a domestic electric circuit, the earth wire is connected to which part of an appliance to ensure safety?
- A)Live wire terminal
- B)Neutral wire terminal
- C)Metallic body of the appliance
- D)Switch mechanism
Answer: C) Metallic body of the appliance
The earth wire connects the metallic body of the appliance to the ground, providing a path for leakage current to flow safely away and preventing electric shock.
Q6.If a straight vertical wire carries current upwards, what is the direction of the magnetic field lines around it when viewed from above?
- A)Clockwise
- B)Anti-clockwise
- C)Radially outward
- D)Radially inward
Answer: B) Anti-clockwise
According to the Right Hand Thumb Rule, if the thumb points up (current direction), the curled fingers indicate an anti-clockwise direction for the magnetic field lines.
Q7.Which physical quantity is measured in kilowatt-hours (kWh)?
- A)Power
- B)Current
- C)Electrical Energy
- D)Voltage
Answer: C) Electrical Energy
Kilowatt-hour is a commercial unit of electrical energy, representing the energy consumed by a 1 kW device running for 1 hour, whereas Power is measured in Watts.
Q8.An electric motor works on the principle of converting:
- A)Mechanical energy into electrical energy
- B)Electrical energy into mechanical energy
- C)Chemical energy into electrical energy
- D)Thermal energy into electrical energy
Answer: B) Electrical energy into mechanical energy
An electric motor utilizes the magnetic effect of current to produce rotational motion, thereby transforming electrical energy into mechanical energy.
Q9.What happens to the total resistance and current in a series circuit if one bulb fuses out?
- A)Resistance decreases, current increases
- B)Resistance increases, current remains same
- C)Resistance becomes infinite, current stops
- D)Resistance stays same, current decreases
Answer: C) Resistance becomes infinite, current stops
In a series circuit, all components are connected in a single path; if one component fails, the circuit becomes open, making resistance effectively infinite and stopping the current flow.
Q10.According to Joule’s Law of Heating, if the current flowing through a resistor is doubled while keeping time and resistance constant, how does the heat produced change?
- A)It doubles
- B)It halves
- C)It quadruples
- D)It remains the same
Answer: C) It quadruples
Joule's Law states that heat produced is directly proportional to the square of the current (H propto I²). Therefore, doubling the current results in four times the original heat produced.