Physics ATP Notes
Q1. How to check for zero error in a:
(i) Vernier caliper
(ii) Micrometer screw gauge
(iii) Meter rule
(iv) Stopwatch
Ans:
(i) Close the jaws of the vernier caliper fully. When the zeros of both MAIN SCALE and
VERNIER SCALE are not aligned together, the zero error is present.
(ii) Before placing an object, turn the thimble until the spindle and anvil meet. If the reading
on the thimble is not alligned with the zero mark on the datum line, a zero error is present.
(iii) Refer to this.
(iv) Just check what the stopwatch reads on reset. If it isn't 00:00, a zero-error is present.
Readings are subtracted accordingly.
Q2/3. How to check for zero error in a:
(i) Voltmeter
(ii Ammeter?
Ans: For both of them, disconnect them (from the circuit) and check if the pointer is pointing
at the zero mark on the scale. If they aren't, a zero-error is present.
Q4/5. Why the pointer reading ammeter/voltmeter is gently tapped before taking a reading?
Ans: To reduce the friction between the needle and the pivot.
Q6. When making a ray diagram, why should rays and normal be as thin as possible?
Ans: Thin lines make it possible to obtain precise readings; with thick lines it is difficult to
measure accurate angles (of incidence, reflection etc.).
Q7. What is the purpose of a rachet in a micrometer?
Ans: To prevent undue pressure from being exerted.
Gcecompilation.com | O Level and A level Resources
, Q8. A liquid reaching the maximum temperature quickly. Give one reason.
Ans: It is due to convectional currents. The water expands and gains heat energy and its
density lowers down, and it moves upwards and the lower part of the apparatus is replaced
by cold water which has higher density.
Q9. Why is the temperature 20°C marked on the measuring cylinder?
Ans: The scale on the cylinder is calibrated to give accurate readings when the liquid is at
20°C.
Q10. Why an image is measured from a position behind the screen rather than front?
Ans: If it was measured from the front, it would block the rays of light and disturb the
apparatus.
Q11: WHAT IS A MEANT “GOOD ELECTRICAL” CONNECTION?
Ans: It means that the components are connected properly and are tightly screwed in the
circuit. This also reduces the circuit's internal resistance.
Q14: STATE ONE PRECAUTION, OTHER THAN AVOIDING PARALLAX ERROR THAT
SHOULD TAKE WHEN USING A SCHOOL LAB THERMOMETER, TO ENSURE
ACCURATE MEASUREMENT OF TEMPERATURE?
Ans: Check the mercury level when the reading becomes steady. If the thermometer is in a
liquid, make sure it is 1/3rd immersed and that the liquid is stirred before taking the reading.
Q16: WHAT IS THE AFFECT OF “LENGTH” OR “MASS” ON TIME PERIOD OF
PENDULUM?
Ans: Length - The period of a pendulum increases with length.
Mass - No effect.
Q17: WHAT ARE THE CONDITIONS TO GET ACCURATE FIXED POINTS?
Ans: Immerse 1/3rd of the thermometer into the funnel containing ice, avoid parallax error
when reading the temperature on the thermometer, use ice shavings to ensure good
contact between the bulb of the thermometer and the ice, wait for the temperature to
become steady before taking the reading, etc. Ice point is 0°C and steam point is 100°C.
Q18: WHY WHILE DETERMINING THE BOILING POINT OF WATER, THERMOMETER IS
HELD IN STEAM?
Gcecompilation.com | O Level and A level Resources
Q1. How to check for zero error in a:
(i) Vernier caliper
(ii) Micrometer screw gauge
(iii) Meter rule
(iv) Stopwatch
Ans:
(i) Close the jaws of the vernier caliper fully. When the zeros of both MAIN SCALE and
VERNIER SCALE are not aligned together, the zero error is present.
(ii) Before placing an object, turn the thimble until the spindle and anvil meet. If the reading
on the thimble is not alligned with the zero mark on the datum line, a zero error is present.
(iii) Refer to this.
(iv) Just check what the stopwatch reads on reset. If it isn't 00:00, a zero-error is present.
Readings are subtracted accordingly.
Q2/3. How to check for zero error in a:
(i) Voltmeter
(ii Ammeter?
Ans: For both of them, disconnect them (from the circuit) and check if the pointer is pointing
at the zero mark on the scale. If they aren't, a zero-error is present.
Q4/5. Why the pointer reading ammeter/voltmeter is gently tapped before taking a reading?
Ans: To reduce the friction between the needle and the pivot.
Q6. When making a ray diagram, why should rays and normal be as thin as possible?
Ans: Thin lines make it possible to obtain precise readings; with thick lines it is difficult to
measure accurate angles (of incidence, reflection etc.).
Q7. What is the purpose of a rachet in a micrometer?
Ans: To prevent undue pressure from being exerted.
Gcecompilation.com | O Level and A level Resources
, Q8. A liquid reaching the maximum temperature quickly. Give one reason.
Ans: It is due to convectional currents. The water expands and gains heat energy and its
density lowers down, and it moves upwards and the lower part of the apparatus is replaced
by cold water which has higher density.
Q9. Why is the temperature 20°C marked on the measuring cylinder?
Ans: The scale on the cylinder is calibrated to give accurate readings when the liquid is at
20°C.
Q10. Why an image is measured from a position behind the screen rather than front?
Ans: If it was measured from the front, it would block the rays of light and disturb the
apparatus.
Q11: WHAT IS A MEANT “GOOD ELECTRICAL” CONNECTION?
Ans: It means that the components are connected properly and are tightly screwed in the
circuit. This also reduces the circuit's internal resistance.
Q14: STATE ONE PRECAUTION, OTHER THAN AVOIDING PARALLAX ERROR THAT
SHOULD TAKE WHEN USING A SCHOOL LAB THERMOMETER, TO ENSURE
ACCURATE MEASUREMENT OF TEMPERATURE?
Ans: Check the mercury level when the reading becomes steady. If the thermometer is in a
liquid, make sure it is 1/3rd immersed and that the liquid is stirred before taking the reading.
Q16: WHAT IS THE AFFECT OF “LENGTH” OR “MASS” ON TIME PERIOD OF
PENDULUM?
Ans: Length - The period of a pendulum increases with length.
Mass - No effect.
Q17: WHAT ARE THE CONDITIONS TO GET ACCURATE FIXED POINTS?
Ans: Immerse 1/3rd of the thermometer into the funnel containing ice, avoid parallax error
when reading the temperature on the thermometer, use ice shavings to ensure good
contact between the bulb of the thermometer and the ice, wait for the temperature to
become steady before taking the reading, etc. Ice point is 0°C and steam point is 100°C.
Q18: WHY WHILE DETERMINING THE BOILING POINT OF WATER, THERMOMETER IS
HELD IN STEAM?
Gcecompilation.com | O Level and A level Resources
