Month: January 2020

Question:What is a magnetic field? Answer:The area surrounding the magnet under the influence of the magnetic force. Question 2:Figure 1 shows an iron nail coiled with insulated copper wire connected to a dry cell of 1.5 V.(a) What happens when the switch is turned on?(b) Mark the direction of the current flow in the copper … Read more

Question:Aim: To study the pattern and direction of the magnetic field produced by the electric current that flows through different conductors.Materials: Straight wire, coiled wire, thin cardboard, solenoid and iron filingsApparatus: Compass, retort stand with clamp, power supply (D.C. 3 V), connecting wire and crocodile clipInstruction1. Set up the apparatus as shown in Figure 7.17.2. … Read more

Question:Aim: To study the pattern of a magnetic field.Materials: Iron filings and a piece of thin cardApparatus: Bar magnet, horseshoe magnet, magnadur magnet, compass and drawing paperInstruction1. Sprinkle some iron filings evenly on a thin piece of card. (Photograph 7.15).2. Place the card on a piece of bar magnet (Photograph 7.16) and tap the card … Read more

Question 1:Draw a parallel circuit using three bulbs, a dry cell, a switch and several connecting wires. Answer: Question 2:Based on Figure 1, calculate:(a) the effective resistance(b) the current in the circuit(c) the voltage across each resistor Answer:(a) R = 1 Ω + 3 Ω + 5 Ω    = 9 Ω(b)\(I=\frac{9 \mathrm{~V}}{9 \Omega}=1 \mathrm{~A}\)(c) … Read more

Activity 7.8:Aim: To study current, voltage and resistance in a parallel circuit.Apparatus: Dry cell holder, connecting wire, switch, bulb (1.5 V), dry cell, ammeter and voltmeterInstruction1. Set up a parallel circuit as shown in Figure 7.11 (a).2. Turn on the switch and measure the current that flows through bulb M. Measure the current that flows … Read more

Activity 7.7:Aim: To study current, voltage and resistance in a series circuit.Apparatus: Dry cell holder, connecting wire, bulb (1.5 V), dry cell, switch, ammeter and voltmeterInstruction1. Set up a series circuit as shown in Figure 7.10 (a).2. Turn on the switch and measure the current that flows through bulb M. Measure the current that flows … Read more

Question 1:State the forms of energy that exists in each of the following situations.(a) Boiling water(b) A chicken running(c) Compressed spring Answer:(i) Heat energy(ii) Kinetic energy(iii) Elastic potential energy Question 2:As the clouds move, a lot of electric charges are accumulated by the clouds.Based on the statement above, explain the occurrence of lightning. Answer:The clouds … Read more

Experiment 7.1:Aim: To study the effects of changes in resistance and voltage on electric current.(A) The effect of changes in resistance on electric currentProblem statement: What is the effect of changes in resistance on electric current?Hypothesis: The higher the resistance, the smaller the current flow.Variables:(a) Constant variable: Number of dry cells(b) Manipulated variable: The length … Read more

Activity 7.6:Aim: To measure the current and voltage by using a suitable measuring apparatus.Apparatus: Ammeter, voltmeter, connecting wire, switch, dry cell, crocodile clip, bulb and dry cell holder(A) Measuring current using an ammeterInstruction1. Connect the circuit as shown in Photograph 7.8 using one dry cell.2. Turn on the switch and record the reading of the … Read more

Activity 7.5:Aim: To study the relationship between electric charges and electric current.Apparatus: Van de Graaff generator, galvanometer and connecting wireInstruction1. Set up the apparatus as shown in Figure 7.7.2. Switch on the Van de Graaff generator and observe the pointer on the galvanometer.Questions1. What happens to the galvanometer’s pointer? Explain.2. How do you show the … Read more