1
GATE PI 2012
MCQ (Single Correct Answer)
+1
-0.3
For an opaque surface, the absorptivity $$\left( \alpha \right),$$ transmissivity $$\left( \tau \right)$$ and reflectivity $$\left( \rho \right)$$ are related by the equation:
A
$$\alpha + \rho = \tau $$
B
$$\rho + \alpha + \tau = 0$$
C
$$\alpha + \rho = 1$$
D
$$\alpha + \rho = 0$$
2
GATE PI 2012
MCQ (Single Correct Answer)
+2
-0.6
Consider two infinitely long thin concentric tubes of circular cross section as shown in the figure. If $${D_1}$$ and $${D_2}$$ are the diameters of the inner and outer tubes respectively, then the view factor $${F_{22}}$$ is given by GATE PI 2012 Heat Transfer - Radiation Question 1 English
A
$$\left( {{{{D_2}} \over {{D_1}}}} \right) - 1$$
B
Zero
C
$$\left( {{{{D_1}} \over {{D_2}}}} \right)$$
D
$$1 - \left( {{{{D_1}} \over {{D_2}}}} \right)$$
3
GATE PI 2012
MCQ (Single Correct Answer)
+2
-0.6
In a $$DC$$ $$arc$$ welding operating, the length characteristic was obtained as $${V_{arc}} = 20 + 5l$$ where the $$arc$$ length $$l$$ was varied between $$5mm$$ and $$7mm.$$ Here $${V_{arc}}$$ denotes the arc voltage in volts. The $$arc$$ current was varied from $$400A$$ to $$500A.$$ Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are
A
$$45V, 450A$$
B
$$75V, 750A$$
C
$$95V, 950A$$
D
$$150V, 1500A$$
4
GATE PI 2012
MCQ (Single Correct Answer)
+2
-0.6
In a shaping process, the number of double strokes per minute is $$30$$ and the quick return ratio is $$0.6,$$ If the length of the stroke is $$250mm,$$ the average cutting velocity in $$m/min$$ is
A
$$3.0$$
B
$$4.5$$
C
$$7.5$$
D
$$12.0$$
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