Five characteristics of electron?

Aroll in a paper machine is powered by a separately excited dc machine. operating point 1 (under load): the roll typically operates at 764 rpm and must provide 301 nm of torque to oppose the load of the paper. the armature voltage is 230v for this operating point operating point 2 (no load): when the load is removed the speed of the roll increases to 900 rpm (the field characteristics are unchanged) la ea dev m (a) calculate the maximum torque (units of nm) that the motor can supply with this applied voltage (b) calculate the value of the armature resistance, ra (in ohms) (c) at operating point 1 (loaded condition), the field current, i, and the total input power (armature field), are measured to be to be 10 a and 28,600 w respectively. use this information to calculate the value of the field resistance, rf (in ohms). (d) (d) at operating point 1 (loaded condition), calculate the motor efficiency. express your answer as a percent to at least 2 significant digits. (d) if the field voltage is reduced by 1/2, calculate the new stall torque (in nm) of the motor (f). if the field voltage is reduced by 1/2, calculate the new no-load speed (in rad/sec)

Question 7 [2 marks] in the circuit below, the electromotive force generated by the battery is e = 6.0 v, and the resistances are r1 = r4 = 1.0 q, r2 = r3 =2.0 q. r. the power delivered by the battery to the circuit is closest to a. 6 w в. 12 w с. 15 w d. 18 w e. 20 w final exam autumn 2014 page 5 of 9 68037 physical modelling faculty of science [2 mark] question 8 with reference to question 7, the current through resistor r2 is closest to a. 1 a в. 2 а c. 3 a d. 4 a e. 6 a

An ideal polarizer with its transmission axis rotated 30 degrees to the vertical is placed in a beam of unpolarized light of intensity 10w/m^2. after passing through the polarizer, what is the intensity of the beam? a. 8.7 w/m^2 b. 7.5 w/m^2 c. 5.0 w/m^2 d. 10 w/m^2 e. 2.5 w/m^2