Units and Measurements Test

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Units and Measurements Test - 36

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Weekly Quiz Competition

Question 1
1 / -0

Error due to eye vision is termed as :

A
climax error

B
sight error

C
parallax error

D
visional error

Solution

$$Answer:-$$ C
Parallax also affects optical instruments such as rifle scopes, binoculars,microscope and twin lens reflex cameras that view objects from slightly different angles. Many animals, including humans, have two eyes with overlapping visual fields that use parallax to gain depth perception; this process is known as stereopsis.
Question 2
1 / -0

A star's distance ($$d$$) and its parallax angle ($$p$$) are related to each other as:

A
$$d=\dfrac{1}{p}$$

B
$$d=\dfrac{1}{p^2}$$

C
$$p=\dfrac{1}{d^2}$$

D
none of these

Solution

Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer's point of view.
The relationship between a star's distance and its parallax angle:
$$d=\dfrac{1}{p}$$
The distance $$d$$ is measured in parsecs and the parallax angle $$p$$ is measured in arc seconds.
Question 3
1 / -0

In lab one student obtained a weight measurement of $$3.2 kg$$ for a given substance, but the actual or known weight is $$10 kg$$, then his measurement is :

A
accurate

B
not accurate

C
precised

D
not presiced

Solution

Since the measured value of weight of the substance is far away from the value of actual weight, so the measurement is said to be inaccurate.
Question 4
1 / -0

A physical quantity has term of velocity,and force which are proportional to it .It is known that it does not depend on any other physical quantity ,so its dimension can be,

A
$$ML^{2}T^{-3}$$

B
$$MLT^{3}$$

C
$$ML^{2}T^{3}$$

D
none of the above

Solution

Let, $$x$$ be the physical quantity.
Here, $$x\propto v$$ a $$x\propto F$$ where $$v=$$ velocity and $$F=$$ force
$$x=kvF$$ where $$k=$$ proportionality constant.
Dimensionally, $$[x]=[LT^{-1}][MLT^{-2}]=[ML^2T^{-3}]$$
Question 5
1 / -0

________ refers to the degree of conformity and correctness of something when compared to a true or absolute value. Fill the appropriate answer.

A
Accuracy

B
Precision

C
Accuracy and Precision

D
None of these

Solution

Accuracy is defined as the extent upto which a given measurement agrees with the standard value for that measurement. Accuracy refers to the degree of conformity and correctness of something when compared to a true or absolute value.
Question 6
1 / -0

The extent to which a given measurement agrees with the standard value for that measurement is known as :

A
Accuracy

B
Precision

C
Accuracy and Precision

D
None of these

Solution

Accuracy is defined as the extent upto which a given measurement agrees with the standard value for that measurement.
For example : Actual weight of the given substance is $$10.0 \ kg$$ and the measured value of the mass is $$9.9 \ kg$$. This measurement is said to be accurate.
Question 7
1 / -0

The ratio of dimensions electric field and magnetic field is,

A
$$MT^{1}L^{-1}$$

B
$$MT^{-1}L^{-2}$$

C
$$MT^{2}L^{-1}$$

D
$$LT^{-1}$$

Solution

Electric field $$=$$ force/charge or $$E=F/q$$
So, $$[E]=\dfrac{[MLT^{-2}]}{[IT]}=[MLT^{-3}I^{-1}]$$ where $$[I]=$$ dimension of current.
We know that magnetic force $$F=qvB$$ or $$B=\dfrac{F}{qv}$$
So, $$[B]=\dfrac{[MLT^{-2}]}{[IT][LT^{-1}]}=[MT^{-2}I^{-1}]$$

Thus, $$\dfrac{[E]}{[B]}=\dfrac{[MLT^{-3}I^{-1}]}{MT^{-2}I^{-1}}=[LT^{-1}]$$
Question 8
1 / -0

On dividing dimension of gravitational constant by the dimension of surface tension we get

A
$$M$$

B
$$ML^{2}$$

C
$$M^{-2}L^{3}$$

D
None of he above

Solution

By Newton's law of gravitation, $$F=\dfrac{Gm_1m_2}{r^2}$$ or $$G=\dfrac{Fr^2}{m_1m_2}$$
So, $$[G]=\dfrac{[MLT^{-2}][L^2]}{[M][M]}=[M^{-1}L^3T^{-2}]$$

Surface tension $$=$$ force/length or $$S=F/l$$
So, $$[S]=\dfrac{[MLT^{-2}]}{[L]}=[MT^{-2}]$$

Thus, $$\dfrac{[G]}{[S]}=\dfrac{[M^{-1}L^3T^{-2}]}{[MT^{-2}]}=[M^{-2}L^3]$$
Question 9
1 / -0

The mass of an object is measured by two students (true weight is 12 kg)
Student 1: He measures 12 kg
Student 2: She measures 12.5 kg
Measurement of which student is more accurate.

A
Student 1

B
Student 2

C
Both are equally accurate

D
Cannot be compared.

Solution

Accuracy defines nearness of a measured value to the standard or true value. Since value measured by student 1 is nearer to the actual value $$12 \ kg$$ compared to that measured by student 2. So measurement of student 1 is more accurate.
Question 10
1 / -0

The dimensions of $$\dfrac{QV}{C}$$ is,($$Q$$=charge,$$V$$=voltage,$$C$$=capacitance,take dimension of current as $$k$$)

A
$$M^{2}L^{-4}T^{-6}k^{-1}$$

B
$$M^{2}L^{4}T^{-6}k^{-2}$$

C
$$M^{2}L^{-4}T^{6}k^{-2}$$

D
$$M^{2}L^{4}T^{-6}k^{1}$$

Solution

We know that, $$Q=CV$$ so $$\dfrac{QV}{C}=\dfrac{(CV)V}{C}=V^2$$
So we have to find out only dimension of $$V^2$$
Volatge $$V=Ed=\dfrac{F}{Q}d$$
We know that dimension of force, $$[F]=[MLT^{-2}]$$, distance $$[d]=[L]$$ and charge $$[Q]=[kT]$$ (as charge $$=$$ current$$\times $$ time)
Now, $$[V]=\dfrac{[MLT^{-2}]}{[kT]}[L]=[ML^2T^{-3}k^{-1}]$$
Thus, $$[V^2]=[M^2L^4T^{-6}k^{-2}$$]

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Units and Measurements Test - 36

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Units and Measurements Test - 36

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SHARING IS CARING

Question 1

climax error

sight error

parallax error

visional error

Solution

Question 2

$$d=\dfrac{1}{p}$$

$$d=\dfrac{1}{p^2}$$

$$p=\dfrac{1}{d^2}$$

none of these

Solution

Question 3

accurate

not accurate

precised

not presiced

Solution

Question 4

$$ML^{2}T^{-3}$$

$$MLT^{3}$$

$$ML^{2}T^{3}$$

none of the above

Solution

Question 5

Accuracy

Precision

Accuracy and Precision

None of these

Solution

Question 6

Accuracy

Precision

Accuracy and Precision

None of these

Solution

Question 7

$$MT^{1}L^{-1}$$

$$MT^{-1}L^{-2}$$

$$MT^{2}L^{-1}$$

$$LT^{-1}$$

Solution

Question 8

$$M$$

$$ML^{2}$$

$$M^{-2}L^{3}$$

None of he above

Solution

Question 9

Student 1

Student 2

Both are equally accurate

Cannot be compared.

Solution

Question 10

$$M^{2}L^{-4}T^{-6}k^{-1}$$

$$M^{2}L^{4}T^{-6}k^{-2}$$

$$M^{2}L^{-4}T^{6}k^{-2}$$

$$M^{2}L^{4}T^{-6}k^{1}$$

Solution

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