Q1. Calculate the number of light years in one metre.
Q2. The mass of an electron is 9.11kg.How many electrons would make 1 kg ?
Q3. In defining the standard of length, we have to specify the temperature at which the measurement should be made. Are we justified in calling length a fundamental quantity, if another physical quantity (temperature) has to be specified in choosing a standard ?
Q4. Which type of phenomenon can be used as a measure of time ? Give three examples.
Q5. Why has ‘second’ been defined in terms of periods of radiation from Cesium -133 ?
Q6 Derive the S.I unit of joule (J) in terms of fundamental units.
Q7. What is a coherent system of units ?
Q8. Do AU and A represent the same unit of length ?
Q9. Does magnitude of a quantity change with change in the system of units ?
Q10. Can a body have zero mass and zero weight ?
Q11. Name two types of mass ?
Q12. Is light year a of time ?
Q13. Why is the cylinder used in defining kg made of platinum iridium alloy ?
Q14. What is common between bar and torr ?