The four bulbs of 40 W each are connected in series swift a battery across them, which of the following statement is true?

A box contains 10 electric bulbs from which 2 bulbs are defective . Two bulbs are chosen at random. What is the probability that one of them is defective?

A

3/10

B

16/45

C

25/68

D

8/33

সিরিজে সংযুক্ত একটি এ্যামিটার এবং একটি অজানা রোধ দুটি একই রকম 1.5 V ব্যাটারীর দুই প্রান্তে সংযুক্ত আছে। যখন ব্যাটারী দুটি সিরিজে সংযুক্ত থাকে তখন এ্যামিটার। amp রিডিং প্রদর্শন করে। আবার ব্যাটারী দুটি সমান্তরালে সংযুক্ত করলে 0.6 amp রিডিং প্রদর্শন করে। ব্যাটারীর আভ্যন্তরিন রোধ কত ? (An ammeter and an unknown resistance are connected in series across two identical batteries of each 1.5 V. The ammeter shows current I amp and 0.6 amp when the batteries are connected in series and parallel, respectively. What is the internal resistance of the battery?)

A

13Ω

B

12Ω

C

1Ω

D

0.1Ω

E

23Ω

a box contains 20 electric bulbs , out of which 4 are defective . 2 bulbs are chosen at random from this box . The probability that at least one of these is defective is

A

7/19

B

6/19

C

5/19

D

3/19

A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random form this box. The probability that at least one of these is defective is ___

A

7/19

B

6/19

C

5/19

D

3/19

From a batch of 3000light bulbs, 100 were selected at random and tested. If 5of bulbs on the sample found defective,How many defective bulb will be found in entire batch?

A

15

B

60

C

150

D

300

100 W ও 60 W এর দুটি বৈদ্যুতিক বাল্বকে অনুক্রমিক সমবায়ে যুক্ত করে তড়িৎ সংযোগ দেয়া হলো। তাহলে-(If two bulbs of 100 W and 60 W are connected in series with a voltage source. Then-)

A

100 W এর বাল্বটি উজ্জ্বল ভাবে জ্বলবে।

B

60 W এর বাল্বটি উজ্জ্বল ভাবে জ্বলবে।

C

উভয় বাল্বই সমান ভাবে জ্বলবে।

D

100 W এর বাল্বটি পুড়ে যাবে।

E

60 W এর বাল্বটি পুড়ে যাবে।

Bulbs in street lighting are all connected in

A

Parallel

B

Series

C

Series-parallel

D

End-to-end

The battery is an electrochemical device, which means battery

A

Makes chemicals by mechanical means

B

Uses chemical action to provide electricity

C

Has curved plates instead of flat plates

D

Does not use an electrolyte

In a battery cover is placed over the element and sealed to the top of the battery container. This is done

A

to reduce evaporation of water from electrolyte

B

to exclude dirt and foreign matter from the electrolyte

C

to discharge both of the above functions

D

to discharge none of the above functions

The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures

A

Active power in R phase

B

Active power of Y phase

C

Reactive power of R phase

D

Power proportional to 3 phase power if the load is balanced

The four bulbs of 40 W each are connected in series swift a battery across them, which of the following statement is true?

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