Physics Paper 5 Question 1 Tips

1. To measure the frequency of alternating current power supply, use an oscilloscope.

- First, measure the period from the oscilloscope. T = Time base x horizontal distance.

- f = 1/T

2. To measure the voltage from the oscilloscope

V = y-gain x vertical distance

3. When measuring induced emf, measures to increase the value of induced emf to reduce percentage error are:

- Use more number of turns in the coil.

- Use an iron core inside the coil.

- Apply a high potential difference across the coil.

- Increase frequency of alternating current power supply.

Note: Instead of an oscilloscope, you can use a signal generator to measure frequency. It also gives readings of I and V.

4. Points to include when measuring B using a Hall probe:

- Calibrate the Hall probe with known values of magnetic flux density.

- Rotate the Hall probe until the VH is maximum because that is the angle at which B is perpendicular to the Hall probe.

- Secure or clamp this angle of the Hall probe.

- Repeat the experiment with the Hall probe reversed and average.

5. In light experiments, if you have to change the wavelength of emitted light, place a coloured filter in front of the light source.

Additional details:

- Use an intense light source for accurate readings. Wear safety goggles to protect your eyes from the light.

6. When measuring the diameter of any cylindrical or spherical object, measure 2 or more diameters and take the average.

7. Suppose you rotate a cylindrical lamina using a Motor fitted at its centre. Then, to increase the frequency of rotation, reduce resistance, so the current increases. As a result, the frequency of rotation increases.

8. To measure small thickness, use a Vernier Calliper. To measure mass, use a measuring balance. To calculate volume, use volume = l x b x h. To calculate density, use density = mass/volume.

9. In experiments, where B is measured using current passing through a coil, the safety precautions are:

- Switch off the current when not in use to avoid overheating.

- Do not touch the coil as it is at high temperatures.

10. To push an object or set into motion

- Use spring loaded device to give a start velocity of a set value.

11. For repeating readings, write the statement as:

- Take multiple readings of (Dependent variable) for each value of (Independent Variable) and average.