Electrical Engg (EEE) - MCQ Practice Questions

8-bit 2's complement range is from -2^7 to 2^7-1, which is -128 to +127.

CMOS has minimal static power consumption (only during switching), making it ideal for battery-powered devices.

4GB = 4 × 2^30 bytes = 2^32 bytes. Therefore, 32 address lines are needed (2^32 addresses).

Priority encoders are designed with built-in priority logic where the highest priority input (usually MSB) is encoded when multiple inputs are active.

Gray code ensures only one bit changes between consecutive values, reducing errors in digital transitions and rotary encoders.

Synchronous counters clock all flip-flops at the same time, preventing cumulative propagation delays that cause glitches in asynchronous designs.

CMOS logic has noise margins typically around 30-40% of supply voltage, superior to TTL (~0.4V) and ECL (~0.2V).

De Morgan's law states: (A.B)' = A'+B' (NAND equals OR of inverted inputs) and (A+B)' = A'.B' (NOR equals AND of inverted inputs).

When both S=1 and R=1 in SR flip-flop, both Q and Q' become 1, violating the complementary relationship - this is the forbidden state.

A Johnson counter with n flip-flops generates 2n unique states (half of the theoretical 2^n), making it useful for decade counters.

LUTs in FPGAs are programmable combinational logic blocks that can implement any logic function for inputs (typically 4-6 inputs).

Fan-out (typically 10 for TTL) is the maximum number of logic gate inputs that an output can reliably drive while maintaining specified voltage levels.

The D flip-flop captures input D on clock edge and transfers it to output: Q(n+1) = D. This represents 'data' or 'delay' functionality.

Combinational circuits produce outputs based solely on current inputs. Sequential circuits have memory elements (flip-flops) and outputs depend on input history.

Tristate logic provides high, low, and high-impedance states, enabling multiple devices to connect to a single bus by controlling which device actively drives the line.

Maximum frequency = 1/(4 × propagation delay) = 1/(4 × 10 ns) = 12.5 MHz. For ripple counters, the total delay is n × tpd.

Mealy machines produce outputs based on both the current state and input variables, unlike Moore machines which depend only on the current state. This makes Mealy machines more efficient in detecting sequences.

In a priority encoder with MSB having highest priority, when I7=1 (highest priority input), the output represents position 7, which is 111 in 3-bit binary. Lower priority inputs I5 and I3 are ignored.

The dielectric strength of air at standard conditions (1 atm, 25°C) is approximately $30\text{kV/cm}$. For a 1 cm gap, the breakdown voltage is $30\text{kV/cm}\times 1\text{cm}=30\text{kV}$. This is a fundamental reference value in high voltage engineering.

Paschen's law states that the breakdown voltage $V_b$ of a uniform-field gas gap is a function of the product $pd$, i.e., $V_b=f(pd)$. This is expressed as the Paschen curve, which shows a minimum breakdown voltage at an optimum $pd$ value. Both pressure and gap distance affect breakdown only through their product.