Measurement and Marking Techniques

What is the function of a stopwatch's second hand?

• Measure hours

• Show minutes

• Indicate seconds

• Start timing

Answer explanation

The second hand of a stopwatch is specifically designed to indicate seconds, allowing for precise timing of short intervals. This distinguishes it from the hour and minute hands, which measure longer durations.

Which button resets a stopwatch to zero?

• Start

• Stop

• Reset

• Minute

Answer explanation

The 'Reset' button is specifically designed to set the stopwatch back to zero. The 'Start' and 'Stop' buttons control the timing, while 'Minute' is not relevant for resetting.

Why is the start button important in measuring an event's duration?

• To end the time

• To reset the stopwatch

• To initiate time measurement

• To display seconds only

Answer explanation

The start button is crucial because it initiates time measurement for an event. Without pressing it, the stopwatch remains inactive, making it impossible to track the duration accurately.

What should be done before starting a new time on the stopwatch?

• Check for battery

• Reset to zero

• Adjust the second hand

• Start directly

Answer explanation

Before starting a new time on the stopwatch, it is essential to reset it to zero. This ensures accurate timing for the new interval, preventing any overlap or confusion with previous measurements.

How could an inaccurate reset affect timing?

• Causes stopwatch to display zeros

• Adds extra time

• Stops the watch entirely

• Displays only minutes

Answer explanation

An inaccurate reset can lead to the stopwatch adding extra time, as it may not properly clear previous measurements. This results in cumulative timing errors, making the displayed time longer than intended.

Which instrument measures electric current?

• Voltmeter

• Ammeter

• Stopwatch

• Plumb bob

Answer explanation

An ammeter is the instrument specifically designed to measure electric current, while a voltmeter measures voltage, a stopwatch measures time, and a plumb bob is used for vertical alignment.

Why is it necessary to connect a voltmeter in parallel?

• For circuit resistance

• For direct current measurement

• For accurate voltage readings

• To protect the voltmeter

Answer explanation

Connecting a voltmeter in parallel is necessary for accurate voltage readings because it allows the voltmeter to measure the potential difference across the component without significantly affecting the circuit's operation.

To read an ammeter accurately, what should be done first?

• Place it near the bulb

• Connect it properly in series

• Attach it to a power source

• Reset it to zero

Answer explanation

To read an ammeter accurately, it must be connected properly in series with the circuit. This ensures that the current flows through the ammeter, allowing it to measure the current accurately.

Why might an ammeter malfunction in a parallel circuit?

• It does not display readings

• It causes a short circuit

• It reads voltage instead of current

• It measures the resistance

Answer explanation

An ammeter is designed to measure current and should be connected in series. In a parallel circuit, connecting it directly can cause a short circuit, leading to malfunction and potential damage.

What part of a stopwatch shows 1/10th of a second?

• Second hand

• Minute hand

• 1/10 second hand

• Start button

Answer explanation

The 1/10 second hand on a stopwatch specifically measures tenths of a second, making it the correct part that shows 1/10th of a second. The second hand measures whole seconds, while the minute hand measures minutes.