Q. No.The least count of vernier callipers is \(0.1\) mm. The main scale reading before the zero of the vernier scale is \(10\), and the zeroth division of the vernier scale coincides with any main scale division. If the value of one main scale division is \(1\) mm, the measured value should be expressed as:
1. \(0.010\) cm
2. \(0.001\) cm
3. \(0.1\) cm
4. \(1.00\) cm
[Screw gauge has \(50\) divisions on the circular scale]
1. \(6.8\) cm2
2. \(3.4\) cm2
3. \(3.9\) cm2
4. \(2.4\) cm2
1. \(1.75 \times 10^{-2}\) cm
2. \(180 \times 10^{-2}\) cm
3. \(175 \times 10^{-2}\) cm
4. \(17.5 \) cm
1. \(0.001\) cm
2. \(0.002\) mm
3. \(0.002\) cm
4. \(0.005\) cm
When the circular scale of a screw gauge completes \(2\) rotations, it covers \(1\) mm over the pitch scale. The total number of circular scale divisions is \(50.\) The least count of the screw gauge in metres is:
1. \(10^{-4}\)
2. \(10^{-5}\)
3. \(10^{-2}\)
4. \(10^{-3}\)
A screw gauge has the least count of \(0.01~\text{mm}\) and there are \(50\) divisions in its circular scale. The pitch of the screw gauge is:
| 1. | \(0.25~\text{mm}\) | 2. | \(0.5~\text{mm}\) |
| 3. | \(1.0~\text{mm}\) | 4. | \(0.01~\text{mm}\) |
The main scale of a vernier calliper has \(n\) divisions/cm. \(n\) divisions of the vernier scale coincide with \((n-1)\) divisions of the main scale. The least count of the vernier calliper is:
| 1. | \(\dfrac{1}{(n+1)(n-1)}\) cm | 2. | \(\dfrac{1}{n}\) cm |
| 3. | \(\dfrac{1}{n^{2}}\) cm | 4. | \(\dfrac{1}{(n)(n+1)}\) cm |
Which of the following is the most precise device for measuring length?
| 1. | a vernier calliper with \(20\) divisions on the sliding scale. |
| 2. | a screw gauge of pitch \(1\) mm and \(100\) divisions on the circular scale. |
| 3. | an optical instrument that can measure the length within a wavelength of light. |
| 4. | both (1) and (2) |
A student measures the thickness of a human hair by looking at it through a microscope of magnification \(100.\) He makes \(20\) observations and finds that the average width of the hair in the field of view of the microscope is \(3.5 ~\text{mm}.\) The thickness of the hair is:
1. \(0.035~\text{mm}\)
2. \(0.0035 ~\text {mm}\)
3. \(0.35 ~\text{mm}\)
4. \(3.5 ~\text{mm}\)
| 1. | \(0.02~\text{mm}\) | 2. | \(0.05~\text{mm}\) |
| 3. | \(0.10~\text{mm}\) | 4. | \(0.20~\text{mm}\) |
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