Q4) Ohm’s law applies at constant temperature. The higher the temperature, the higher resistance. Temperature increases with voltage. Incandescent lamps: electrons collide with nuclei. Thus move further from their equilibrium positions. In an uncontrolled experiment. Electrons have trouble going through, kinetic energy is lost as heat when collisions happen. Thus electrons are impeded, so slow down and the current lowers.
Q5) The graph obeys Ohms law between -1 and +1 V as shown by the graph. Resistance is 50/2.3
- Provide a circuit diagram (Figure 3) indicating the direction of conventional current flow.
- Provide a graph (Figure 4) of current (y-axis) vs. voltage (x-axis)
- Provide a sketch-graph of lamp-brightness vs. voltage (Figure 5)
- This circuit does not obey Ohm’s law across this voltage range. Explain why.
- Is there any range of voltage over which this component might be said to obey Ohm’s law? How does the shape of the graph in Figure 5 help you identify this range? Calculate the resistance of the filament in this range.
PART 3: QUESTIONS:
Show your working in each case. Give numerical answers with an appropriate number of significant figures.
- What is the total resistance in a simple DC circuit containing three resistors in series? The values of these resistors are 6.0 Ω, 3.0 Ω and 12.0 Ω.
- What is the total resistance in a simple DC circuit containing three resistors in parallel? The values of these resistors are 2.0 Ω, 4.0 Ω and 8.0 Ω.
- The total resistance in a DC circuit containing three resistors in series is 12.0 Ω. If the values of two of these resistors are 6.0 Ω and 4.0 Ω, what is the value of the third resistor?
- In the following circuit the battery delivers an emf of 12 V. What is the value of the current I, flowing through the ammeter A?
- What is the total resistance of this circuit?
- What is the current through a 400 W electric appliance when it is connected to a 230 V power supply?
- The current flowing through a resistor is in a DC circuit is 73 mA. How many coulombs od charge pass through it in one second? How many electrons pass through it in one second?
- The power dissipated by a resistor of resistance 150 Ω is 50 W. How much current is passing through it?
- A current of 3.6 A flows for 15.3 s through a wire. Calculate the number of electrons passing through a point on the wire during this time.
- How long will it take 2.0 × 1020 electrons to pass through a point in a conductor if the current is 10.0A?