The half-life period of a radioactive element $A$ is 62 years. It decays into another stable element $B$. An archaeologist found a sample in which $A$ and $B$ are in 1:15 ratio. The age of the sample is
The current gain of a transistor in common emitter configuration is 80 . The resistances in collector andbase sides of the circuit are $5 \mathrm{k} \Omega$ and $1 \mathrm{k} \Omega$ respectively. If the input voltage is 2 mV , the output voltage is
4 V
0.4 V
0.8 V
8 V
Four logic gates are connected as shown in the figure. If the inputs are $A=0, B=1$ and $C=1$, then the values of $Y_1$ and $Y_2$ respectively, are

The maximum distance between the transmitting and receiving antennas for satisfactory communication in line of sight mode is 57.6 km . If the height of the receiving antenna is 80 m , the height of the transmitting antenna is (radius of earth $=6.4 \times 10^6 \mathrm{~m}$ )