Related Questions

একটি ধাতব তলে λ তরঙ্গদৈর্ঘ্যের একবর্ণী আলোকরশ্মি আপতিত হলে ফটো-ইলেক্ট্রন নির্গত হয় এবং এক্ষেত্রে বিভবের মান 3Vo একই তলে যখন 2λতরঙ্গদৈর্ঘ্যের একবর্ণী আলো আপতিত হয়, তখন নিবৃত্তি বিভবের মান Vol ফটো-ইলেক্ট্রন নির্গত হওয়ার জন্য ঐ তলটির সূচন তরঙ্গদৈর্ঘ্যের মান নির্ণয় কর।(A monochromatic light of wavelength λ is incident on a metallic surface then ejects photo-electron and the value of stopping potential is 3Vo. When the same surface is illuminated by a light of wavelength 2λ., the stopping potential becomes Vo. Calculate the threshold wavelength for this surface to eject photo electrons.)
A 6λ
B 8λ
C 4λ3
D λ
E 4λ
Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
A Low cost
B Wide speed range
C Stability
D High starting torque
[Rewrite the sentence starting with the part given and bracket below, keeping the meaning changed in question] After three hours of walking the museum, the entire family felt in need of a rest. (The entire family felt in need of a rest)
A walking through the museum for three hours
B having walked through the museum for three hours
C and they walked through the museum for three hours
D despite having walked through the museum for three hours
Japan experiences frequent earth-quakes because it is located ________
A On the eastern coast of Asia
B On the meeting point of two plates of the earth's crust
C Amidst the ocean
D In the volcanic belt
A direct on line starter is used: for starting motors
A Up to 5 H.P.
B Up to 10 H.P.
C Up to 15 H.P.
D Up to 20 H.P.
Which of the following motors is non-self starting ?
A D.C. series motor
B synchronous motor
C Squirrel cage induction motor
D Wound round induction motor
Synchronous motors are generally not self-starting because
A the direction of rotation is not fixed
B the direction of instantaneous torque reverses after half cycle
C startes cannot be used on these machines
D starting winding is not provided on the machines
Star-delta starting of motors is not possible in case of
A Single phase motors
B Variable speed motors
C Low horse power motors
D High speed motors
DOL starting of induction motors is usually restricted to
A Low horsepower motors
B Variable speed motors
C High horsepower motors
D High speed motors
Which of the following motors is inherently self starting ?
A Split motor
B Shaded-pole motor
C Reluctance motor
D None of these

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