TS EAMCET 2017 :: Physics :: General questions

• Physics - General questions

An electron  collides with a hydrogen atom in its ground  state and excites it to n=3 state. The energy  given to the hydrogen atom in this inelastic  collision

(neglecting  the recoil of hydrogen  atom ) is

Answer:

Explanation:

 According to the question,

 Energy  given to hydrogen atom= Difference in energy level from $n_{1}=1 $ to $n_{2}$=3  states

$=13.6\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)=13.6\left(\frac{1}{1^{2}}-\frac{1}{3^{2}}\right)=13.6\left(1-\frac{1}{9}\right)$

 $=13.6 \times \frac{8}{9}=12.08 $ ≈12.1 eV

An object is thrown vertically upward with a speed of 30 m/s. The velocity of the object half -a- second before it reaches the maximum height is

Answer:

Explanation:

 According to the question,

The velocity of an object half a second before the maximum height

= Velocity of an object half a second after maximum height (return journey)

 $0+gt=0+9.8 \times \frac{1}{2}=4.9 m/s$

A wire has resistance of $3.1 \Omega$  at $30^{0} C$  and $4.5 \Omega$  at $100^{0} C$ . The temperature coefficient of resistance  of the wire is 

Answer:

Explanation:

 Given,

 $t_{1}=30^{0}C$

$R_{1}=3.1 \Omega$

$t_{2}=100^{0} C$

$R_{2}=4.5 \Omega$

 we know that,

 temperature  coefficient of resistance,

 $\alpha=\frac{R_{2}-R_{1}}{R_{1}t_{2}-R_{2}t_{1}}=\frac{4.5-3.1}{(3.1)(100)-(4.5 \times 30)}$

  = $\frac{1.4}{310-135}=\frac{1.4}{175}=0.008^{0} C^{-1}$

An AC generator 10V (rms)  at 200 rad/s is connected in series with a $50 \Omega$ resistor, a  400 mH inductor and a $200 \mu F$ capacitor. The rms voltage  across the inductor is 

Answer:

Explanation:

 Given, E= 10 V

     $\omega$= 200 rad/s

  R= 50 $\Omega$

L=400 mH

 C=200 $\mu$ F

 We know that,

    $Z=\sqrt{R^{2}+(X_{L}-X_{c})^{2}}$

     $Z=\sqrt{(50)^{2}+(80-25)^{2}}=\sqrt{(50)^{2}-(55)^{2}}$

$=\sqrt{2500+3025}$

 Z= $\sqrt{5525}=74.3 \Omega$

  $I= \frac{E}{Z}=\frac{10}{74.3}=0.13459 A$

 $E_{L}=IX_{L}=0.13459 \times 80$

  =10.76 V or 10.8 V

Which of the following is emitted , when  $^{239}_{94}Pu$ decays into $^{235}_{92}U$?

Answer:

Explanation:

 $^{239}_{94}Pu$ $\underrightarrow{a}$  $^{235}_{92}U$

 When $\alpha$- particle is emitted that atomic mass is decreases by four and atomic number is decreases by two

• Physics - General questions