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Sketch current-time graphs to compare alternating current and direct current - Leaving Cert Physics - Question b - 2018
Question b
Sketch current-time graphs to compare alternating current and direct current. A rectifier circuit converts alternating current to direct current. Draw a circuit dia... show full transcript
Worked Solution & Example Answer:Sketch current-time graphs to compare alternating current and direct current - Leaving Cert Physics - Question b - 2018
Step 1
Sketch current-time graphs to compare alternating current and direct current.
Answer
To illustrate the difference between alternating current (AC) and direct current (DC), draw two graphs. The graph for AC should be sinusoidal, indicating the periodic change in direction, while the DC graph should be a straight line at a constant value. Be sure to label the axes: time (s) on the x-axis and current (A) on the y-axis. For at least one graph, ensure that the axes are clearly labeled.
Step 2
A rectifier circuit converts alternating current to direct current. Draw a circuit diagram of a half-wave rectifier circuit.
Answer
A half-wave rectifier circuit consists of a diode connected in series with an AC supply. The anode of the diode should connect to the AC source, while the cathode connects to the load resistor. The input voltage (AC) can be labeled at the input side of the diode and the output voltage (DC) across the load resistor. Ensure that the diode symbol is included correctly.
Step 3
Sketch a graph to illustrate the output current from a half-wave rectifier.
Answer
The output current waveform for a half-wave rectifier will be a series of positive pulses corresponding to the positive half-cycles of the input AC voltage. The graph should rise to a peak value during the conduction period of the diode and drop to zero during the non-conducting period. Label the axes: Time (s) on the x-axis and Output Current (A) on the y-axis.
Step 4
Draw a labelled diagram of an induction coil.
Answer
A labelled diagram of an induction coil should include a primary coil connected to a d.c. power supply, a secondary coil, and an iron core. The primary coil should be labeled, indicating its connection to the power source, and the secondary coil should be shown positioned in proximity to the primary coil with the label indicating that it’s the coil with more turns.
Step 5
Describe how the induction coil can be used to increase d.c. voltage.
Answer
An induction coil increases d.c. voltage by utilizing electromagnetic induction. When the primary coil is switched on and off, it creates a changing magnetic field. This changing field induces an electromotive force (emf) in the secondary coil, resulting in a higher voltage output compared to the input voltage, especially when the secondary coil has more turns than the primary.
Step 6
Step 7
Draw a labelled diagram of this device.
Answer
A labelled diagram of a transformer should depict two coils (the primary and secondary), both wound around a common iron core. Clearly indicate the input (primary) and output (secondary) sides, and label the two coils to highlight their roles in the voltage transformation process.
Step 8
Describe how this device can be used to increase a.c. voltage.
Answer
A transformer increases a.c. voltage by utilizing two coils, the primary and secondary, wound around a common iron core. When the alternating current flows through the primary coil, it produces a changing magnetic field. This changing magnetic field induces an electromotive force (emf) in the secondary coil. If the secondary coil has more turns than the primary, the induced voltage in the secondary will be greater than the input voltage, thereby stepping it up.