০৭। A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low pass filter with cut off frequency 800 Hz. The output signal has the frequency.
ক) 0 Hz
খ) 0.75 kHz
গ) 0.5 kHz
ঘ) 0.25 kHz
০৮। A box has 4 white and 3 red balls. Two balls are taken out in succession. What is the probability that both are white?
ক)
খ)
গ)
ঘ)
০৯। A casual LTI system is described by the difference equation 2y[n] = ay[n - 2] - 2x[n] + βx[n -1] The system is stable only if
ক) |a | = 2 |β| < 2
খ) |a | > 2 |β| > 2
গ) |a | < 2 any value of β
ঘ) |β| < 2, any value of a
১০। A casual system having the transfer function is excited with 10 ∪(t). The time at which the output reaches 99% of its steady-state value is
ক) 2.7 sec
খ) 2.5 sec
গ) 2.3 sec
ঘ) 2.1 sec
১১। A complex wave is 5 + 5 sin ωt. Its rms value is
ক) 7.07 V
খ) 5 V
গ) 10 V
ঘ) 6.12 V
১২। A dice is tossed. The probability that either 1 or 2 will appear is
ক)
খ)
গ)
ঘ)
১৩। A discrete LTI system is non-casual if its impulse response is
ক) an ∪(n - 2)
খ) an-2 ∪(n)
গ) an+2 ∪(n)
ঘ) an ∪(n + 2)
১৪। A first order system will never be able to give a __________ response
band stop
band pass
all pass
Choose the correct option
ক) 1, 2, 3 true
খ) 1 and 3 true, 2 false
গ) 1, 2 are true 3 is false
ঘ) 1, 2 are false, 3 is true
১৫। A function having frequency f is to be sampled. The sampling time T should be
ক)
খ)
গ)
ঘ)
১৬। A function will have only sine terms if
ক) f(t) = - f(t)
খ) f(-t) = f(t)
গ) f(-t) = -f(t)
ঘ) none of the above
১৭। A gate function which occurs at t = t0 and lasts for duration T can be written as
ক) u (t - t0 - T)
খ) u(t - t0) = u(t - t0 - T)
গ) u(t - t0) - u(t - t0 - T)
ঘ) u(t - t0) - u(t - t0 + T)
১৮। A linear discrete time system has the char. equation z3 - 0.81z = 0, the system is
ক) stable
খ) marginally stable
গ) unstable
ঘ) stability cannot be assessed from the given information
১৯। A linear system is characterized by H(ω) = Be-2ω2 the system is physically