Order of Magnitude

Q.

What is smaller than a second?

Q.

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 is 3.5 mm. What is the estimate on the thickness of the hair:

(a) 0.0035 mm (b) 0.035 mm

(c)0.01 mm (d) 0.7 mm

Q. Two persons $A$ and $B$ perform the same amount of work in moving a body through a certain distance $d$ with application of forces acting at angles ${45}^{\circ }$ and ${60}^{\circ }$ with the direction of displacement respectively. The ratio of force applied by person $A$ to the force applied by person $B$ is $\frac{1}{\sqrt{x}}$. The value of x is .

Q.

The wavelength of light that has a frequency of $1.20\times {10}^{13}{s}^{-1}$ is __________ m

Q. It takes time $8$ min for light to reach from sun to the earth surface. If speed of light is taken to be $3\times {10}^8$ m $s^{-1}$, find the order of magnitude of distance from the sun to the earth in km.

1. ${10}^{7}km$
2. $15\times {10}^{8}km$
3. ${10}^{8}km$
   
4. ${10}^{9}km$

Q.

1 nano metre (1nm) is equal to

1. 10^-7 m

2. 10^-9 m

3. 10⁹ m

4. none of these

Q. If the linear charge density of a rod of length $3\text{m}$ varies as $\lambda =(2+x)\frac{\text{C}}{\text{m}}$, where $x$ is the distance from one end of the rod, then find the total charge on the rod.

1. $21\text{C}$
2. $5.5\text{C}$
3. $10.5\text{C}$
4. $5\text{C}$

Q. A variable force $\overline{F}-(x^2\hat{i}+xy\hat{j})$ N is acting on a particle which from point (0, 0) to (1 m, 2 m) along the path OAB as shown. Find work done by force.

1. $\left(\frac{1}{3}\right)$ J
2. $\left(\frac{5}{3}\right)$ J
3. $\left(\frac{7}{3}\right)$ J
4. 2J

Q.

Name two sub-multiples of metrecube.

Q. Considering the rules of the significant figures, what is the value of $10.01\text{m}\times 9.11\text{m}$?

1. $91.19$
2. $91.1911$
3. $91.191$
4. $91.2$

Q.

Cross the odd one out.

Litre, kilometre, centimetre, light year.

Q.

How many bits are there in a byte?

1. $4$

2. $6$

3. $8$

4. $12$

Q. A force varying with distance is given as $F=a{e}^{-bx}$ acts on a particle of mass $m$ moving in a straight line. Find the work done on the particle if it is displaced by a distance $d$ from the origin.

1. $\frac{a}{b}(1-e^{-bd})$
2. $\frac{b}{a}(1-e^{-bd})$
3. $\frac{a}{b}\left(e^{-bd}\right)$
4. $\frac{b}{a}\left(e^{-bd}\right)$

Q.

What is meant by the order of magnitude of a quantity?

Q.

The speed of light in vacuum is 3 x 10⁸ $m{s}^{-1}$.

1. True
2. False

Q. Name the three convenient units used to measure length ranging from very short to very long value. How are they related to the S.I. unit?

Q. Name any two units of length which are bigger than the metre. Write the relation
between each of those units and the metre.

Q. The order of magnitude of seconds in a day is ${10}^x$. What is $x$.

Q. State whether the following statement is True or False.

1. True
2. False

Q.

Which of the following is greater than$1000.01$?

1. $0.0010001\times {10}^7$

2. $0.00001\times {10}^8$

3. $1.1\times {10}^2$

4. $1.00001\times {10}^3$

Q.

How many $cm$ equals $1km$ and how?

Q.

The wavelength of the light is usually represented in

1. micron

2. fermi

3. nanometer

4. angstrom

Q. The order of magnitude of 0.00701 is:

1. 2
2. 1
3. -3
4. -1

Q. Write the order of magnitude of mass of an electron $9.1\times {10}^{-31}$ kg.

Q. Order of magnitude of 7000000 is

1. 6
2. 7
3. 5
4. 8

Q. Each computer connected to the internet must

1. be an IBM PC
2. have a unique IP address
3. be internet compatible
4. . have a modem connection

Q. A.500.0 mm B.50.0 cm C.0.500 m D.5.0*10^-4 km It is given that out of these four values A is most accurate as it has maximum significant figures but significant figure only represent precision not accuracy so all should be equally accurate as they are equally close to the same value??

Q. The prefix used for denoting an order of magnitude of ${10}^6$ is ___________.

1. Giga
2. Kilo
3. Mega
4. Micro

Q. What is the order of magnitude of one light year?

1. ${10}^{15}m$
2. ${10}^{10}m$
3. $9.2\times {10}^{15}m$
4. ${10}^{16}m$

Q. Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelengths ${\lambda }_1:{\lambda }_2$ emitted in the two cases is

1. $\frac{27}{5}$
2. $\frac{7}{5}$
3. $\frac{20}{7}$
4. $\frac{27}{20}$