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Level 2 Worksheet: Magnetic Effects of Electric Current

Class: 10 Science Topic: Logic, Numericals & Reasoning Max. Questions: 50
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Section A: Direction & Logic (1-15)
  1. A positively charged particle (alpha particle) projected towards the West is deflected towards the North by a magnetic field. Determine the direction of the magnetic field.
  2. An electron enters a magnetic field at right angles to it moving from West to East. The field is acting vertically downwards. What is the direction of the force experienced by the electron?
  3. A constant current flows in a horizontal wire in the plane of the paper from East to West. What is the direction of the magnetic field at a point (a) North of the wire, (b) South of the wire?
  4. Imagine you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from the back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of the magnetic field?
  5. A proton is moving towards the East. A magnetic field is acting vertically upwards. Find the direction of the force on the proton.
  6. State the rule to find the direction of magnetic field produced moving from south to north in a straight wire.
  7. Current in a horizontal power line flows from East to West. What is the direction of magnetic field at a point directly below it?
  8. A circular loop carries current in clockwise direction when viewed from top. What is the polarity of the top face?
  9. Uniform magnetic field exists in the plane of paper pointing from left to right. An electron enters the field moving from lower to upper edge of the paper. Direction of force?
  10. Does a neutron moving in a magnetic field experience any force? Explain.
  11. Two parallel wires carry current in the same direction. Will they attract or repel each other? (Concept logic).
  12. A vertical wire carries current upwards. A compass is placed to the East of the wire. In which direction will the North pole of the compass point?
  13. If the current in a coil is reversed, what happens to the magnetic field pattern and polarity?
  14. Can we have a single magnetic pole? Why or why not?
  15. How does the magnetic field line pattern change if we use a AC source instead of DC in a straight wire?
Section B: Circuit Analysis & Diagrams (16-30)
  1. Draw a schematic diagram of a domestic electric circuit connecting a bulb, a fan, and a socket to mains. Show the Live, Neutral and Earth connections clearly.
  2. Explain the function of a fuse in a circuit diagrammatically (where is it placed related to meter and switch?).
  3. A 3-pin plug is used for an electric iron. Name the three pins and their function. Why is the top pin thicker and longer?
  4. You are given a coil of copper wire, a battery and a switch. How can you determine the North and South pole of the coil without a compass? (Suspension/Repulsion methods).
  5. Draw the magnetic field pattern of a solenoid. How does it resemble a bar magnet?
  6. Identify the mistake in a circuit where the switch is connected to the neutral wire. What is the specific hazard?
  7. In a household circuit, explain why we connect appliances in parallel. Using a circuit diagram logic, show what happens if one breaks in series.
  8. Draw diagram of an electric motor and label: Split Rings, Brushes, Armature.
  9. What is the role of brushes in the motor? If brushes are removed, will the motor work?
  10. A solenoid has a soft iron core. Draw the magnetic field lines. How does the core affect the density of lines?
  11. Explain the concept of 'Short Circuit' using a simple circuit diagram concept (Path of least resistance).
  12. Draw a diagram to show the magnetic field lines around a circular loop. Mark the direction of field at the center if current is clockwise.
  13. What is the polarity of the end of a solenoid if the current appears anti-clockwise to an observer?
  14. Diagrammatically show how to induce current in a coil using a bar magnet.
  15. In an experiment to show Oersted's observation, where should the wire be placed relative to the compass needle to see maximum deflection?
Section C: Numericals & Safety (31-40)
  1. An electric oven of 2 kW power rating is operated in a domestic circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain with calculation.
  2. Calculate the current drawn by an electric iron of 1000 W connected to a 220 V line. What should be the ideal fuse rating?
  3. Two bulbs 100W and 60W are connected in parallel to 220V supply. Which one draws more current? Calculate ratio.
  4. A house has 10 bulbs of 40W each used for 5 hours a day. Find the electrical energy consumed in a day in kWh.
  5. A fuse wire melts at 5A. If it is used in a circuit with a 1.5 kW heater at 220V, will it work? Justify.
  6. What is the resistance of a 100W bulb working at 220V? ($P=V^2/R$).
  7. If the voltage drops to 110V for a 220V-rated heater, how does the heat produced change? (Assume R constant).
  8. A length of wire carries a steady current. It is bent first to form a circular coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. How does the magnetic field at the center compare in the two cases?
  9. Calculate the power of an appliance if it draws 4.5A from a 220V source.
  10. A 1000W heater and 500W toaster are connected in parallel. What is the total current drawn from 220V line?
Section D: Scientific Reasoning (41-50)
  1. Why is the earth wire thicker than the other two wires in a domestic circuit?
  2. Why does the magnetic field inside a long solenoid appear uniform? Explain based on field line pattern.
  3. Why is series arrangement not used for domestic circuits? Give two scientific reasons.
  4. Why is it necessary to earth metallic appliances like electric iron and toaster? Explain the physics of protection.
  5. Why do two magnetic field lines NOT intersect? Justify your answer using the property of tangent (direction).
  6. Why is soft iron used for making electromagnets and not steel? Explain based on retentivity.
  7. Why does the compass needle deflect when brought near a current carrying wire?
  8. Force on a current carrying conductor is maximum when it is perpendicular to the field. Why? (Concept of cross product/angle dependence).
  9. Why are copper and aluminum wires usually used for electricity transmission?
  10. Why is AC preferred over DC for long distance transmission of electric power?