Electromagnetism: Grade 11 Past Paper Questions

The graph below shows the change in magnetic flux (ΔΦ) versus the change in time (Δt) as the bar magnet moves through the solenoid. 8.2 Use the graph to calculate the rate of change of magnetic flux linked to the coil. 8.3 Calculate the magnitude of the EMF induced across the coil if the coil has 120 turns. 8.4 State TWO ways by which the induced EMF in the coil can be increased.

5.2 A square coil with sides of length 0,25 m contains 200 turns and is positioned perpendicular to a uniform magnetic field of magnitude 0,75 T. The coil is then quickly pulled from the field in 0,20 s, moving perpendicular to the magnetic field, to a region where there is no magnetic field. 5.2.1 State Faraday's Law of electromagnetic induction in words. 5.2.2 Calculate the emf induced across the coil.

QUESTION 6. A circular coil with 150 turns is placed in a uniform magnetic field of strength 0,5 T. The plane of the coil initially makes an angle of 40° with the magnetic field, as shown in Diagram 1 below. The coil is uniformly rotated in 0,2 seconds so that its plane is parallel to the magnetic field, as shown in Diagram 2 below. During this rotation, the induced emf in the coil is 0,43 V. 6.1 State Faraday's law of electromagnetic induction in words. 6.2 Calculate the change in magnetic flux during the rotation of the coil. 6.3 Determine the area of one turn of the circular coil.

1.8 The north pole of a bar magnet is pushed into a solenoid, as shown in the sketch below. The polarity of X on the solenoid and the direction of flow of the induced current through the solenoid will be... 1.9 The ampere second (A·s) is the unit for A. Current strength B. Quantity of charge C. Resistance D. Potential difference.

7.2 R is a point charge of magnitude +6 nC. 7.2.1 Draw the electric field pattern for charge R. S is a point charge of magnitude −9 nC placed 25 mm to the right of R. Z is a point x mm east of point charge S. Point charges R and S, and point Z lie on the same line. 7.2.2 State Coulomb's law in words. 7.2.3 Calculate the magnitude of the electrostatic force that charge R exerts on charge S. The net electric field at Z is 7,66×10⁴ N·C⁻¹ west. 7.2.4 Calculate the value of x in metres. QUESTION 8. A bar magnet moves horizontally towards a solenoid. 8.1 State Faraday's Law of electromagnetic induction in words.

1.5 The diagram below shows a magnet that is moved towards a solenoid. Which ONE of the following combinations are CORRECT? A. North, X to Y B. North, Y to X C. South, X to Y D. South, Y to X. 1.6 Which ONE of the following graphs best represents the relationship between the electrical power (P) dissipated by a resistor and the potential difference (V) across the resistor if the resistance of the resistor remains constant? 1.7 Which ONE of the following is the unit of measurement for the rate of flow of charge? A. Coulomb B. Ampere C. Volts D. Watts.

QUESTION 1. 1.1 Two forces P and Q act at a point O. As the angle θ between P and Q varies, the MAXIMUM and MINIMUM resultant forces are 13 N and 3 N respectively. The magnitudes of the two forces are: A. 3 N and 10 N B. 16 N and 10 N C. 8 N and 5 N D. 10 N and 7 N. 1.2 A passenger standing in a moving bus moves forward when the bus suddenly stops. This can best be explained by A. Newton's First law of motion B. Newton's Second law of motion C. Newton's Third law of motion D. Newton's law of Universal gravitation. 1.3 A learner sits on a chair. What is the reaction force to her sitting on the chair? A. Force that the learner exerts on the chair. B. Weight of the learner. C. Force that the chair exerts on the learner. D. Force that the learner exerts on Earth. 1.5 A car, moving to the right along a rough horizontal surface, is brought to rest by a constant net force. If the motion to the right is taken as positive, which ONE of the following acceleration versus time graphs is correct for the motion of the car? 1.6 The graphs P, Q, R and S drawn below show a relationship between the force of attraction that two masses exert on each other and the inverse of the square of the distance between their centres. In which graph will the product of their masses be the largest? A. P B. Q C. R D. S. 1.7 The force of attraction between two charges q₁ and q₂ is F. If the distance between the charges is made four times smaller, then the new force of attraction will be... A. 0,5F B. 1,78F C. 2,5F D. 16F. 1.8 The north pole of a bar magnet is pushed into a solenoid, as shown in the sketch below. The polarity of X on the solenoid and the direction of flow of the induced current through the solenoid will be... 1.9 The ampere second (A·s) is the unit for A. Current strength B. Quantity of charge C. Resistance D. Potential difference. 1.10 Which ONE of the following graphs represents the relationship between the total electrical energy transferred (W) and the electric current (I) in the element of a kettle? The resistance of the element and the time for which the current flows are constant. QUESTION 2. Three forces Fₐ, F_B and F_C act on a point O in the directions shown in the diagram below. The magnitudes of Fₐ and F_C are 44 N and 31 N respectively. The magnitude of F_B is unknown. The forces are NOT drawn to scale. 2.1 Define the term resultant vector. The resultant of the three forces is 26,69 N at an angle of 25,82° to the horizontal, and lies in the first quadrant. 2.2 Calculate the magnitude of F_B. 2.3 Determine θ.

7.2.3 Calculate the magnitude of the electrostatic force that charge R exerts on charge S. The net electric field at Z is 7,66×10⁴ N·C⁻¹ west. 7.2.4 Calculate the value of x in metres. QUESTION 8. A bar magnet moves horizontally towards a solenoid. 8.1 State Faraday's Law of electromagnetic induction in words. The graph below shows the change in magnetic flux (ΔΦ) versus the change in time (Δt) as the bar magnet moves through the solenoid. 8.2 Use the graph to calculate the rate of change of magnetic flux linked to the coil. 8.3 Calculate the magnitude of the EMF induced across the coil if the coil has 120 turns. 8.4 State TWO ways by which the induced EMF in the coil can be increased.

5.2 A square coil with sides of length 0,25 m contains 200 turns and is positioned perpendicular to a uniform magnetic field of magnitude 0,75 T. The coil is then quickly pulled from the field in 0,20 s, moving perpendicular to the magnetic field, to a region where there is no magnetic field. 5.2.1 State Faraday's Law of electromagnetic induction in words. 5.2.2 Calculate the emf induced across the coil. QUESTION 6. 6.1 State Ohm's Law in words. A battery with an internal resistance of 0,5 Ω and an unknown emf (ε) is connected to four resistors and a switch as shown in the circuit below. A high-resistance voltmeter (V) is connected across the battery. A₁ and A₂ are ammeters of negligible resistance. With switch S closed, the current passing through the 8 Ω resistor is 0,5 A, and resistor R delivers 12 W of power. 6.2 Calculate: 6.2.1 The reading on ammeter A₁ 6.2.2 The reading on ammeter A₂ 6.2.3 The emf of the battery (ε).

QUESTION 1. 1.1 Two forces, F₁ and F₂, act simultaneously at a point. The resultant force is 17 N when they act in the same direction, and 5 N when they act in opposite directions. The magnitude of the two forces are: A. 14 N and 3 N B. 11 N and 6 N C. 5 N and 12 N D. 10 N and 7 N. 1.2 A person stands on a bathroom scale that is calibrated in newton, in a stationary elevator. The reading on the bathroom scale is W. The elevator now moves downward with a constant acceleration of ¼g, where g is the gravitational acceleration on Earth. What will the reading on the bathroom scale now be? A. ¼W B. ¾W C. W D. 5/4 W. 1.3 Two objects of masses 2m and m are arranged as shown in the diagram below. Which of the following changes will result in the largest increase in the gravitational force the two objects exert on each other? A. Double the mass of each object. B. Double the larger mass and double the distance between their centres. C. Double the larger mass and halve the distance between their centres. D. Triple the smaller mass and halve the distance between their centres. 1.4 Two charges, +Q and −Q, are each placed a distance d from a negative charge −q. The charges, +Q and −Q, are located along lines that are perpendicular to each other, as shown in the diagram below. Which ONE of the following arrows CORRECTLY shows the direction of the net force acting on charge −q due to the presence of charges +Q and −Q? 1.5 The diagram below shows a magnet that is moved towards a solenoid. Which ONE of the following combinations are CORRECT? A. North, X to Y B. North, Y to X C. South, X to Y D. South, Y to X. 1.6 Which ONE of the following graphs best represents the relationship between the electrical power (P) dissipated by a resistor and the potential difference (V) across the resistor if the resistance of the resistor remains constant? 1.7 Which ONE of the following is the unit of measurement for the rate of flow of charge? A. Coulomb B. Ampere C. Volts D. Watts. QUESTION 2. Two forces act simultaneously on a small boat in a flat part of a river: the motor exerts a force of 1 200 N at an angle of 40° north of east; the river current exerts a force of 800 N in a northerly direction. The boat is at point O. 2.1 Define the term resultant vector. 2.2 Using an accurate scale drawing, determine the magnitude and direction of the resultant force acting on the boat. Use the scale 1 cm : 200 N.

QUESTION 6. A circular coil with 150 turns is placed in a uniform magnetic field of strength 0,5 T. The plane of the coil initially makes an angle of 40° with the magnetic field, as shown in Diagram 1 below. The coil is uniformly rotated in 0,2 seconds so that its plane is parallel to the magnetic field, as shown in Diagram 2 below. During this rotation, the induced emf in the coil is 0,43 V. 6.1 State Faraday's law of electromagnetic induction in words. 6.2 Calculate the change in magnetic flux during the rotation of the coil. 6.3 Determine the area of one turn of the circular coil. QUESTION 7. Three resistors and a light bulb are connected to a battery with an emf (ε) of 12 V and an unknown internal resistance (r) as shown in the diagram below. The ammeter and connecting wires have negligible resistance. The voltmeter reads 4,8 V when the switch is closed. 7.1 Define the term power in words. 7.2 Calculate the: 7.2.1 Effective resistance of the parallel combination 7.2.2 Reading on the ammeter.