# A d.c. motor develops a torque of 200 N-m at 25 rps. At 20 rps it will develop a torque of .......... N-m.

A d.c. motor develops a torque of 200 N-m at 25 rps. At 20 rps it will develop a torque of .......... N-m.

A d.c. motor develops a torque of 200 N-m at 25 rps. At 20 rps it will develop a torque of 200 N-m.

## Related questions

Description :  A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent increase in armature current. The new value of torque is: A) 102.5 N-m B) 202.5 N-m C) 172.5 N-m D) 232.5 N-m

Last Answer : T1=KIf,T2=K1.5I*0.9f T1=150Nm.  T2=T1*1.5*0.9=150*1.35=202.5Nm

Description : A 220 V shunt motor develops a torque of 54 N-m at armature current of 10 A. The torque produced when the armature current is 20 A, is?

Last Answer : Armature torque, Ta=PØZIa/2πA So Ta1/Ta2=Ia1/Ia2 Ta2=Ta1*Ia2/Ia1        =54*20/10         =108

Description : Between no-load and full-load, .......... motor develops the least torque.

Description : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :

Last Answer : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075

Description : A 200 V, 10 A motor could be rewound for 100 V, 20 A by using .......... as many turns per coil of wire, having .......... the cross-sectional area.

Last Answer : A 200 V, 10 A motor could be rewound for 100 V, 20 A by using half, as many turns per coil of wire, having twice the cross-sectional area.

Description : Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πND where, N = speed of the rolls ... V.W.Dr.ρ (B) 3.6 V.W. ρ (C) 3.6 W.Dr.ρ (D) 3.6 V.W.Dr/ρ

Last Answer : (A) 3.6 V.W.Dr.ρ

Description : Critical speed of rotation, N (in rps - rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec 2 and, r = radius of trammel, metre.) (A) (1/2π). √(g/r) (B) (1/π). √(g/r) (C) ½ √(g/r) (D) 2π. √(g/r)

Last Answer : (A) (1/2π). √(g/r)

Description : As compared to shunt and compound motors, series motor has the highest torque because of its comparatively .......... at the start.

Last Answer : As compared to shunt and compound motors, series motor has the highest torque because of its comparatively stronger series field at the start.

Description : The shaft torque of a d.c. motor is less than its armature torque because of .......... losses.

Last Answer : The shaft torque of a d.c. motor is less than its armature torque because of rotational losses.

Description : In a d.c. motor, unidirectional torque is produced with the help of

Last Answer : Commutator provides unidirectional torque and pulsating dc

Last Answer : Torque developed by a D.C. motor depends upon magnetic field, active length of the conductor, current flow through the conductors, number of conductors, radius of armature.

Description : If a three-phase induction motor is operated under a light load and it develops an open in one of its supply lines, the motor will _____________. A. continue to run, but will vibrate and have reduced ... speed up due to the reduced number of poles C. run cooler due to reduced current flow D. stop

Description : An induction motor having full load torque of 60 Nm when delta connected develops a starting torque of 120 Nm. For the same supply voltage if the motor is changed to star connection, the starting torque developed will be  A) 40 Nm B) 60 Nm C) 90 Nm D) 120 Nm

Last Answer : An induction motor having full load torque of 60 Nm when delta connected develops a starting torque of 120 Nm. For the same supply voltage if the motor is changed to star connection, the starting torque developed will be 40 Nm

Description : Torque and bending moment of 100 kN.m and 200 kN.m acts on a shaft which has external diameter twice of internal diameter. What is the external diameter of the shaft which is subjected to a maximum shear stress of 90 N/mm2? a. 116.5 mm b. 233.025 mm c. 587.1 mm d. 900 mm

Last Answer : c. 587.1 mm

Description : What is the maximum shear stress induced in a solid shaft of 50 mm diameter which is subjected to both bending moment and torque of 300 kN.mm and 200 kN.mm respectively? a. 9.11 N/mm2 b. 14.69 N/mm2 c. 16.22 N/mm2 d. 20.98 N/mm2

Last Answer : b. 14.69 N/mm2

Description : If the static deflection is 1.665×10 -3 m, calculate the critical speed of the shaft in rps. Centre of disc at 0.25m away from centre of axis of shaft. A. 8.64 B. 9.64 C. 10.64 D. 12.2

Description : An electric motor drives a windless which hauls up a crate A of weight W = 500 kg up an inclined plane through a height of 10 m in 2 minutes. The torque acting on the windless is 25 kgm and the drum of the ... The efficiency of the inclined plane would be a.0.41 b.0.61 c.0.265 d.0.5305 e.0.66

Description : The maximum torque of d.c. motors is limited by?

Last Answer : The maximum torque of d.c. motors is limited by commutation.

Last Answer : For constant torque drive armature voltage control speed control method is preferred.

Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be

Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m

Description : A separately excited d.c. motor fed from single phase full converter with firing angle 60° runs at 1000 r.p.m. If motor is connected to single phase semiconverter with the same firing angle of 60°, it would run at (a) 2000 rpm (b) 1850 rpm (c) 1500 rpm (d) 1000 rpm

Description : The induced e.m.f. in the armature conductors of a d.c. motor is?

Last Answer : The induced e.m.f. in the armature conductors of a d.c. motor is sinusoidal.

Description : The counter e.m.f. of a d.c. motor?

Last Answer : The counter e.m.f. of a d.c. motor helps in energy conversion.

Last Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.

Description : The primary function of an electric motor is to ___________. A. develop torque B. generate high voltages C. produce a magnetic field D. generate high electrical resistance

Description : A synchronous motor starts as usual but fails to develop its full torque. What could it be due to?

Last Answer : a. Exciter voltage may be too low. b. Field spool may be reversed c. There may be either open-circuit or short-circuit in the field.

Description : The d.c. series motor should always be started with load because (A) at no load, it will rotate at dangerously high speed. (B) it will fail to start. (C) it will not develop high starting torque. (D) all are true.

Last Answer : (A) at no load, it will rotate at dangerously high speed.

Last Answer : A synchronous motor can develop synchronous torque at synchronous speed.

Description : A rotary system has a damping coefficient of 40 N-m-sec/rad. The damping torque at a velocity of 2 rad/s, will be A) 20 N-m B) 40 N-m C) 80 N-m D) 100 N-m

Last Answer : C) 80 N-m

Description : A engine will generate maximum torque when it a. runs at maximum speed b. develops maximum power c. runs at lowest speed d. consumes more fuel

Description : A body is executing simple harmonic motion of amplitude 1 cm. Its velocitywhile passing through the central point is 10 mm/sec. Its frequency will be a.2.99 rps b.2.22 rps c.1 rps d.1.59 rps e.1.77 rps

Last Answer : c. 1 rps

Description : Which is the microprocessor launched by Rockwell international: a. RPS-4 b. RPS-6 c. RPS-8 d. All of these

Description : Which is the microprocessor launched by Motorola corporation introduced: a. Mc6800 b. 8080 c. IMP-8 d. RPS-8

Description : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W

Last Answer : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are 240 W

Description : Which of the following statements is not true about somatic embryogenesis? (a) The pattern of development of a somatic embryo is comparable to that of a zygotic embryo. (b) Somatic embryos can develop from ... an auxin such as 2, 4-D. (d) A somatic embryo develops from a somatic cell.

Last Answer : (b) Somatic embryos can develop from microspores.

Description : Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? (a) Ovules develop into embryo sac. (b) Ovary develops into fruit. (c) Zygote develops into embryo. (d) Central cell develops into endosperm

Last Answer : (a) Ovules develop into embryo sac.

Description : Which of the following best illustrates feedback in development? (a) Tissue X secretes RNA which changes the development of tissue Y. (b) As tissue X develops, it secretes enzymes that inhibit the ... . (d) As tissue X develops, it secretes something that slows down the growth of tissue Y.

Last Answer : (c) As tissue X develops, it secretes something that induces tissue Y to develop

Description : What external changes are visible after the last moult of a cockroach nymph? (a) Both forewings and hindwings develop (b) Labium develops (c) Mandibles become harder (d) Anal cerci develop

Last Answer : (a) Both forewings and hindwings develop

Description : Tolerance does not develop to the vasodilator action of sodium nitroprusside while it develops to glyceryl trinitrate because: A. Intact sod. nitroprusside molecule acts like nitric oxide B. Enzymes which ... a long duration of action D. Sod. nitroprusside has additional K+ channel opening action

Last Answer : B. Enzymes which generate nitric oxide from nitroprusside are different

Description : A 3-year-old boy gets seizures whenever he develops fever. Which is the most appropriate strategy so that he does not develop febrile convulsions: A. Treat fever with paracetamol and ... Continuous diazepam prophylaxis for 3 years D. Intermittent diazepam prophylaxis started at the onset of fever

Last Answer : D. Intermittent diazepam prophylaxis started at the onset of fever

Description : Explain the necessity of starter for D.C. motor. State various types of D.C. motor starter.

Last Answer : Necessity of Starter for D.C. Motor: Armature current is given by equation Ia = (V−Eb)/Ra i) If the motor is at standstill or rest, back emf Eb is zero (as Eb= ZNP/(60A), at start speed N ... . Types of D.C. motor starters: i) Two point starter ii)Three point starter iii) Four point starter

Description : State at least one function and the material used for the following parts of DC Motor.

Last Answer : Part Function Material Yoke -Provides mechanical support for poles -Acts as protecting cover for machine -Provides path for magnetic flux Cast Iron OR Cast Steel Field Winding - ... Pole core  Provides mechanical support to field winding. Cast Iron OR Cast Steel

Description : Why shouldn’t a DC shunt motor start on the heavy load setting?

Last Answer : A series motor never started at no load and a shunt motor is never started at on load.

Description : What will happen when a DC shunt motor is started with a load?

Last Answer : Starting current will be very high so motor will take more current from supply. It may damage the armature winding.

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description : If a d.c. motor is disconnected from the source and armature circuit is short circuited through a suitable resistance, the process is called (a) regenerative breaking (b) rheostatic breaking (c) dynamic breaking (d) no breaking is possible

Last Answer : b) rheostatic breaking Because rheostat is connected to chang the power dissipated into heat.

Description : With the increase in load on a d.c. shunt motor, speed of the motor (a) increases proportionately (b) remains constant (c) increase slightly (d) reduces slightly

Last Answer : With the increase in load on a d.c. shunt motor, speed of the motor reduces slightly.

Description : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to  (A) 0.75 p.u (B) 0.5 p.u (C) 0.25 p.u (D) 0.125 p.u

Last Answer : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u

Description : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. The armature of generator is ... value of this load resistance is  (A) 1.0 (B) 0.98 (C) 0.96 (D) 0.94

Last Answer : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. ... obtain rated armature current in both motor and generator. The p.u value of this load resistance is 0.96