41.

The circuit given below represents which of logic operations?

 

• AND

• NOT

• OR

• NOR

Flash light equipped with a new set of batteries, produces bright white light. As the batteries wear out

• the light intensity gets reduced with no change in its colour

• light colour changes first to yellow and then red with no change in intensity

• it stops working suddenly while giving white light

• colour changes to red and also intensity gets reduced

If a  street light of mass Mis suspended from the end of a uniform rod of length L in different possible patterns as shown in figure, then

• pattern A is more sturdy

• pattern B is more study

• pattern C is more sturdy

• all will have same sturdiness

${}_{98}{}^{238}\mathrm{U}$ has  92  protons  and  238  nucleons. It decays by emitting an alpha particle and becomes

• ${}_{92}{}^{238}\mathrm{U}$

• ${}_{90}{}^{234}\mathrm{Th}$

• ${}_{92}{}^{235}\mathrm{U}$

• ${}_{93}{}^{237}\mathrm{Np}$

The foil bone has a ¹⁴C : ¹²C  ratio, which is  [ 1/16 ] of  that in a living animal bone. If the half-life time of  ¹⁴C  is  5730 years, then the age of the fossil bone is

• 11460 years

• 17190 years

• 22920 years

• 45840 years

Which one of the following is a possible nuclear reaction?

• ${}_5{}^{10}\mathrm{B} + {}_2{}^4\mathrm{He} \to {}_7{}^{13}\mathrm{N} + {}_1{}^1\mathrm{H}$

• ${}_{11}{}^{23}\mathrm{Na} + {}_1{}^1\mathrm{H} \to {}_{10}{}^{ 20}\mathrm{Ne} + {}_2{}^4\mathrm{He}$

• ${}_{93}{}^{239}\mathrm{Np} \to {}_{94}{}^{239}\mathrm{Pu} + {\mathrm{\beta }}^{-} + \overline{\mathrm{\nu }}$

• ${}_7{}^{11}\mathrm{N} + {}_1{}^1\mathrm{H} \to {}_6{}^{12}\mathrm{C} + {\mathrm{\beta }}^{-} + \overline{\mathrm{\nu }}$

If alpha, beta and gamma rays carry same momentum, which has the longest wavelength?

• Alpha rays

• Beta rays

• Gamma rays

• None, all have same wavelength

An amplifier  has a voltage gain A_v = 1000. The voltage gain in dB is

• 30 dB

• 60 dB

• 3 dB

• 20 dB

A light emitting diode (LED) has a voltage drop of 2 volt across it and passes a current of  10 mA when it operates with a 6 volt battery through a limiting resistor R. The value of R is

• 40 kΩ

• 4 kΩ

• 200 kΩ

• 400 kΩ

The minimum potential difference between the base and emitter required to switched a silicon transistor ON is approximately

• 1 V

• 3 V

• 5 V

• 4.2 V