Problem set 38

1. Merit of a solar cell or fill factor is
1. $I_mV_m/I_{SC}V_{OC}$
2. $I_mV_{OC}/I_{SC}V_{m}$
3. $I_{SC}V_{OC}/I_{m}V_{m}$
4. $I_{SC}V_{m}/I_{m}V_{OC}$
(A) $I_mV_m/I_{SC}V_{OC}$
2. The resonant frequency of a Heartly oscillator with $L_1=12\mu H$, $L_2=8\mu H$ and $C=1000PF$ is:
1. 1.12 MHz
2. 11.2 MHz
3. 11.2 kHz
4. 112 kHz
$$f_r=\frac{1}{2\pi\sqrt{L_TC}}$$ where, ${\scriptstyle L_T=L_1+L_2=12+8=20\mu H=20\times10^{-6}H}$, ${\scriptstyle C=1000PF=1000\times10^{-12}=10^{-9}F}$ $$\begin{align*} f_r&=\frac{1}{2\times3.14\sqrt{20\times10^{-6}\times10^{-9}}}\\ &=1.12 MHz \end{align*}$$ Hence, answer is (A)
3. In an open loop differential operational amplifier having gain of $A=2\times10^5$ receives inputs as at non-inverting terminal $5\mu V$ and at inverting terminal $-7\mu V$, then the output is:
1. 2.4 V
2. 0.24 V
3. 2.4 mV
4. 2.4 $\mu$V
$$\begin{align*} V_o&=-A(V_2-V_1)\\ &=2\times10^5(5-(-7))\times10^{-6}\\ &=2.4V \end{align*}$$ Hence, answer is (A)
4. The number of Full-adders and Half-adders required to addd 16-bit numbers is
1. 1 HA and 15 FA
2. 8 HA and 08 FA
3. 16 HA and 0 FA
4. 4 HA and 12 FA
(A) 1 HA and 15 FA
5. Sum of all the three inputs will appear as output from:
1. A 3-input NAND gate followed by an inverter
2. A 3-input XOR gate followed by an inverter
3. A 3-input NOR gate followed by an inverter
4. An inverter followed by 3-input NOR gate
Three input NOR gate has output $Z=\bar{X+Y+W}$. Hence, this followed by an inverter will give sum of all the three inputs.
Hence, answer is (A)