In an experiment to determine the e/m value for an electron using Thomson's method the electrostatic deflection plates were 0.01 m apart and had a potential difference of 200 volts applied. Then the electric field strength between the plates is 

1. $1\times {10}^4<mspace\; width="1em"></mspace>V/m$ 

2. $2\times {10}^4<mspace\; width="1em"></mspace>V/m$

3. $4\times {10}^4<mspace\; width="1em"></mspace>V/m$ 

4. $5\times {10}^5<mspace\; width="1em"></mspace>V/m$

To explain his theory, Bohr used

1. conservation of linear momentum

2. conservation of angular momentum

3. conservation of quantum  frequency

4. conservation of energy

which of the following is positively charged?

1.  $\mathrm{\alpha }-\mathrm{particles}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

2.  $\mathrm{\beta }-\mathrm{particles}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

3.  $\mathrm{\gamma }-\mathrm{rays}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

4.  $\mathrm{X}-\mathrm{rays}$

Bragg's law for X-rays is:

1. dsin$\theta$ = 2n$\lambda$ 

2. 2dsin$\theta$ = n$\lambda$

3. nsin$\theta$ = 2$\lambda$d

4. None of these

The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volt is equal to 

1. $\frac{eV}{hc}$ 

2. $\frac{eh}{cV}$ 

3. $\frac{hc}{eV}$ 

4. $\frac{cV}{eh}$

The wavelength of $K_{\alpha }$ X-rays for lead isotopes $P{b}^{208},<mspace\; width="1em"></mspace>P{b}^{206},<mspace\; width="1em"></mspace>P{b}^{204}<mspace\; width="1em"></mspace>are<mspace\; width="1em"></mspace>{\lambda }_1,<mspace\; width="1em"></mspace>{\lambda }_2<mspace\; width="1em"></mspace>and<mspace\; width="1em"></mspace>{\lambda }_3$ respectively. Then

1. ${\lambda }_1={\lambda }_2>{\lambda }_3$   

2. ${\lambda }_1>{\lambda }_2>{\lambda }_3$

3. ${\lambda }_1<{\lambda }_2<{\lambda }_3$ 

4. ${\lambda }_2={\lambda }_1={\lambda }_3$

The graph between the square root of the frequency of a specific line of the characteristic spectrum of X-rays and the atomic number of the target will be:

1.
2.
3.
4.