A2 Physics SYNOPTIC questions! Plz Help!

1) Describe how a coil, together with any other apparatus you require, could be used to detect the presence of a steady magnetic field in the region of a bar magnet. [4 marks]

2) To measure the internal resistance of a cell, a student uses the circuit show in the attached image (see image 1 below). Explain how, by taking readings with the switch S first open and then closed, the student can find the value of r. Suggest a value for the fixed resistor R when r is 40 ohms. [4 marks]

3) A 4700 micro farad capacitor is charged to 25V and discharged through a tightly wound bundle of fine insulated wire, as shown in the attached image (see image 2 below). Explain why it would be difficult to use this arrangement to demonstrate that the Energy stored in the capicitor is Proportional to the square of the Voltage for a range of potential differences up to about 50V. [5 marks]

Thx in advance for ur help! :biggrin:

synoptic.JPG12.2KB

synoptic2.JPG16.9KB

Reply 1

devesh254

OP

anyone....????

Reply 2

VCVT17

2

devesh254

1) Describe how a coil, together with any other apparatus you require, could be used to detect the presence of a steady magnetic field in the region of a bar magnet. [4 marks]

2) To measure the internal resistance of a cell, a student uses the circuit show in the attached image (see image 1 below). Explain how, by taking readings with the switch S first open and then closed, the student can find the value of r. Suggest a value for the fixed resistor R when r is 40 ohms. [4 marks]

3) A 4700 micro farad capacitor is charged to 25V and discharged through a tightly wound bundle of fine insulated wire, as shown in the attached image (see image 2 below). Explain why it would be difficult to use this arrangement to demonstrate that the Energy stored in the capicitor is Proportional to the square of the Voltage for a range of potential differences up to about 50V. [5 marks]

Thx in advance for ur help! :biggrin:

First question:
As well as Faraday experiment: Using the coil connected to the galvanometer.
When the magnet is moved into the coil, the galvanometer pointer gives a momentary deflection showing that a current had been induced in the coil. So there is an indication that bar magnet has a steady magnetic field thourgh it.

Second question:
I think It must need the current through the R resistor and the current through the voltmeter. Because the voltmeter might affects on the correct value of r. So using the formula:
IR = E - Ir
You will find the value of the r.
The suitable value for R is must greater or equal to the value of r. It means the value of R must be 100 Ohm or more...

Sorry I haven't thought of the last question before post...
I will do it later.

Reply 3

VCVT17

2

The last question:
Energy stored in the capacitor:
E = 1/2 CV^2 = 1/2* 4700*10^-9*25^2
= 1.5 *10^-3 J
Its energy is too small to recognise by any lab. tools. Sothat eventhough the potential differences up to 50V.
To demonstrate that energy is proportional to squared of voltages use the light bulb or LED. to measure the amount of energy given out from capacitor. Then adjust voltages for experiment.

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