• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2

# Measurement of capacitance by reed switch

Extracts from this document...

Introduction

881798.doc        p./

 School Class (No.) (      ) Name Subject AL Practical Physics Date Mark

C10   Measurement of capacitance by reed switch

### Procedure

1.        Connect the circuit. Set the resistance of the variable resistor at its maximum value. Record the reading of the voltmeter.

Voltage = ______ 5.9 __________V

4.        Decrease the resistance of the variable resistor slowly until the current shown on the microammeter does not increase any more. Record the reading of the microammeter.

5.

Middle

200

250

300

350

Current (I) / μA

1200

2000

2500

3200

3600

4300

Note that low switching frequency is advised since for high one, the reed switch may not be sensitive enough to respond, and the time may be too short for complete discharge.

6.        Plot a graph of frequency (f) against current (I).

Results and Discussion

1.        Why the charging and discharging of the capacitor must be complete?

If the charging of the capacitor is not complete, the voltage of the capacitor will not reach

that measured by the voltmeter, and the formula I = fVC will be invalid. The same

Conclusion

used.

(b) From I = fCV, since the capacitance of the capacitor is so small, high switching

frequency and high voltage have to be provided to give measurable current. However, the

switching frequency of the reed switch is not too high, since for high one, the reed switch

may not be sensitive enough to respond, and the time may be too short for complete

discharge. Also the voltage is not too high, otherwise, the heating effect at the contact

points of the reed switch may be too large.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related AS and A Level Electrical & Thermal Physics essays

1. ## Test of the reed switch capacitors in series and in parallel

3 star(s)

until some 'Zee' sound was heard from the reed switch, which meant the reed switch was operating.

2. ## Investigating the Capacitance of a Parallel-Plate.

Hence, the current can be measured. Experimental Setup Circuit diagram * All investigations are being done under frequency (f) = 400 Hz as set in the signal generator. Investigation 1: Charge and Applied Potential Difference We separate the capacitor plates with 4 polythene spacers, one at each corner.

1. ## Measurement of capacitance by reed switch.

The reading of the voltmeter was recorded. 2. The coil of the reed switch is connected to a signal generator. The frequency of the signal generator was adjusted to 400Hz. 3. The signal generator was turned on. The voltage output was increased until a buzzing sound from the reed switch could be heard.

2. ## AC Generator

EDISON VS WESTINGHOUSE * In the late nineteenth century Edison chose generating and supplying direct current (DC). * In the same period of time as Edison with DC, Westinghouse promoted the use of alternating current (AC) * Edison had the initial advantage that the technology for generating DC was well

1. ## Investigating the Smoothing Effect of a Capacitor on a Resistive Load

There are two categories under which errors can be regarded as; systematic errors and random errors. Systematic errors occur often when there are faults in the apparatus i.e calibration faults and zeroing of the apparatus. Random errors are also called human errors and are a result of the experimenter's technique.

2. ## A capacitance meter.

In a stable or standby state, the output of the circuit is approximately zero or a logic-low level. When external trigger pulse is applied output is forced to go high (? VCC). The external RC network connected to the timer determines the time for which output remains high.

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to