Skip to main content

Telegraphone was developed by whom ?

Telegraphone was developed by whom ?
1.Vladimir Zworykin
2.Valdemar Poulsen
3.Leon Cooper
4.Samuel F. B. Morse
5.None of these










Answer – 2.Valdemar Poulsen
Explanation :
Telegraphone is a device was developed by Valdemar Poulsen. He invented the telegraphone and developed the first practical device for recording and replaying sound
Labels:

Comments

Post a Comment

Popular posts from this blog

It takes 10 days for digging a trench of 100 m long, 50 m broad and 10 m deep. What length of trench, 25 m broad and 15 m deep can be dug in 30 days ?

 It takes 10 days for digging a trench of 100 m long, 50 m broad and 10 m deep.  What length of trench, 25 m broad and 15 m deep can be dug in 30 days ?       a) 400 m          b) 200 m          c) 100 m          d) 89m Expl : More days, more length (Direct)       Less breadth, more length (Indirect)       More depth, less length (Indirect       Days      10 : 30;       Breadth  25 : 50;                  : : 100 : x       Depth    15 : 10;                     :. 10 * 25* 15 * x = 30 *50 * 10 *100             x= (30*50*10*100)/10*25*15 = 400      So the required length = 400m
Post a Comment
Read more

Find the number of perfect squares in the given series 2013, 2020, 2027,.

Find the number of perfect squares in the given series 2013, 2020, 2027,................, 2300   (Hint 44^2=1936) a. 1   b. 2    c. 3   d. Can’t be determined Answer: a Explanation: The given series is an AP with common difference of 7. So the terms in the above series are in the form of 2013 + 7k.  We have to find the perfect squares in this format in the given series. Given that 44^2 = 1936. Shortcut: To find the next perfect square, add 45th odd number to 44^2. So 45^2 = 1936 + (2 x 45 -1) = 2025 46^2 = 2025 + (2 x 46 - 1) = 2116 47^2 = 2116 + (2 x 47 - 1) = 2209 Now subtract 2013 from the above numbers and divide by 7. Only 2209 is in the format of 2013 + 7k.  One number satisfies.
Post a Comment
Read more