Accuracy and Precision of Instruments

The measured length of two rods are $l_1=30 \mathrm{cm} \pm 0.5 \mathrm{cm}$  and $l_2=20 \mathrm{cm} \pm 0.1 \mathrm{cm}$. The percentage error in difference of length of rods is

Two clocks are being tested against a standard clock located in a national laboratory. At $02:30:00$ pm by the standard clock, the readings of the two clocks are:

The deviation shown by the two clocks in a week are:

Which of the following are correct statements?

(a) Precision refers to the closeness of various measurements for the same quantity.

(b) Accuracy is the agreement of particular values to the true value of the result.

(c) Accuracy is the closeness of various measurements for the same quantity.

Which of the following measurements is most precise?

If the standard deviation of a data is $0.012$. Find the variance

State whether true or false. If false, correct the statement.
With the help of vernier caliper, we can have an accuracy of $0.1 \mathrm{mm}$ and with screw gauge we can have an accuracy of $0.01 \mathrm{mm}$.

To calculate the effective length of pendulum, we measure :-

Closeness of two or more measured values is called as

The pitch of a screw gauge is $0.5 \mathrm{mm}$ and its head scale has $50$ divisions. The least count of the screw gauge is:

The most precise measurement among the following is 

The pitch of a screw gauge is $0.5 \mathrm{mm}$ and its head scale has $50$ divisions. The least count of the screw gauge is:

The period of oscillation of a simple pendulum is $T=2\pi \sqrt{\frac{L}{g}}$. Measured value of $L$ is $20.0 \mathrm{cm}$ known to $1 \mathrm{mm}$ accuracy and time for $100$ oscillations of the pendulum is found to be $90 \mathrm{s}$ using a wristwatch of $1 \mathrm{s}$resolution. The accuracy in the determination of $g$ is

The least count of a measuring scale is $1 \mathrm{mm}$. The heights two students is measured with it. What will be the error in the difference between their heights?

A student measures the length of a piece of a pencil by meter ruler, vernier calipers and screw gauge. Here, the _____ is the device with the highest accuracy and precision.

The figure given above indicates good accuracy and poor precision.

The least count of a measuring scale is $1 \mathrm{mm}$. The heights two students is measured with it. What will be the error in the difference between their heights?

Write any two factors on which accuracy of a measurement depend?

The least count of a measuring scale is $1 \mathrm{mm}$. The heights two students is measured with it. What will be the error in the difference between their heights?

Define accuracy of measurement.

A unit of area, often used in measuring land areas, is the hectare defined as ${10}^4$ ${\mathrm{m}}^2$. An open-pit coal mine consumes 75 hectares of land, down to a depth of 26 m, each year. What volume of earth, in cubic kilometre, is removed in this time?