Ch-2 Physical quantities and measurements

Subjective Questions

1. Differentiate between laboratory thermometer and clinical thermometer.

A laboratory thermometer is used to measure a wide range of temperatures in laboratories, usually from -10°C to 110°C, and does not have a kink. A clinical thermometer is used to measure body temperature, usually ranges from 35°C to 42°C, and has a kink to prevent mercury from falling back.

2. How is digital clock different from stopwatch? What are the uses of stopwatch?

A digital clock displays the current time continuously, while a stopwatch is used to measure time intervals. A stopwatch is used in laboratories, sports events, and other experiments to measure short time intervals accurately.

3. What is the use of kink in clinical thermometer?

The kink in a clinical thermometer prevents the mercury from flowing back into the bulb, allowing the temperature to remain fixed even after removing it from the patient's body.

4. List down the conventions that we follow while writing units. Give an example wherever necessary.

(a) Unit symbols should not be followed by a full stop.
(b) A space is left between the number and the unit symbol (e.g., 5 m).
(c) Symbols are written in lowercase (except for units named after a person, like N for Newton).
(d) Plural is not used with unit symbols.
Example: 10 kg, not 10 kgs.

5. Distinguish between multiples and submultiples of units.

Multiples of units are larger units formed by multiplying the base unit (e.g., kilometer = 1000 meters). Submultiples are smaller units formed by dividing the base unit (e.g., centimeter = 1/100 of a meter).