List of practice Questions

In a transformer $N_p$ = 500, $N_s$ = 5000. Input voltage is 20 V and frequency is 50 Hz. What are the output voltage and frequency ?
In a superheterodyne receiver, the IF is 455 kHz. If it is tuned 1200 kHz, the image frequency will be
In a survey of $100$ students, the number of students studying the various languages were found to be : English only $18$, English but not Hindi $23$, English and Sanskrit $8$, English $26$, Sanskrit $48$, Sanskrit and Hindi $8$, no language $24$. Find How many students were studying English and Hindi?
In a series $LCR$ circuit the voltage across an inductor, capacitor and resistor are $20\,V$, $20\,V$ and $40\,V$ respectively. The phase difference between the applied voltage and the current in the circuit is
In a series of 2n observations half of them equal a and remaining half equal - a. If the standard deviation of the observations is 2, then |a| equals
In a shotput event an athlete throws the shotput of mass $10\, kg$ with an initial speed of $1 \,m/s$ at $45^?$ from a height $1.5 \,m$ above ground. Assuming air resistance to be negligible and acceleration due to gravity to be $10\, m/s^2$, the kinetic energy of the shotput when it just reaches the ground will be
In a reversible isothermal process,the change in internal energy is :
In a rocket of mass 1000 kg, fuel is consumed at a rate of $40\,kgs^{-1}$ The velocity of gases ejected from rocket is $5\times10^4\,ms^{-1}$ . The thrust on rocket is
In a series $LCR$ circuit, the phase difference between the voltage and the current is $45^?$. Then the power factor will be
In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be
In a reaction involving ring substitution of $C_6H_5Y$ the major product is meta isomer. The group Y can be
In a population per capita birth rate is $0.15$ and per capita death rate is $0.08$ during a unit time period. What is the value of $r$ (intrinsic rate of natural increase) for the given population ?
In a projectile motion, the velocity is perpendicular to acceleration at.
In a plane e.m. wave, magnetic field oscillates sinusoidally with frequency 1 GHz. If its amplitude is $16 \times 10^{-8}$ T then amplitude of electric field is
In a polymer sample, 30% of molecules have a molecular mass of 20,000, 40% have 30,000 and the rest 60,000. What is the weight average molecular mass of the polymer ?
In a polymerase chain reaction, temperature required for the steps (i) Denaturation, (ii) Annealing and (iii) Extension are respectively
In a non leap year the probability of getting 53 Sundays or 53 Tuesdays or 53 Thursdays
In a normal embryosac, the ploidy level of egg cell, polar nuclei, synergids and secondary nucleus is
In a p-n junction diode, the increase in forward voltage of 0.19 V increases the forward current by 37.6 mA. The dynamic resistance of the junction is
In a leap year the probability of having 53 Sundays or 53 Mondays is
In a mature dicot stem which has undergone secondary growth, youngest layer of secondary xylem is situated
In a hexagonal close packed structure (hcp) of spheres, the fraction of the volume occupied by the sphere is A. In a cubic close packed structure, the fraction is B. The relation for A and B is
In a hydrogen atom the total energy of electron is
In a hydrogen atom, the radius of $n^{th}$ Bohr orbit is $r_n$. The graph between $log(r_n/r_1)$ and $logn$ will be
In a group of students, mean weight of boys is 80 kg and mean weight of girls is 50 kg. If the mean weight of all the students taken together is 60 kg, then the ratio of the number of boys so that of girls is