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marissa [1.9K]
3 years ago
8

Why is a convex lens useful for starting fires

Physics
1 answer:
Anika [276]3 years ago
7 0

because if you were stuck on an island and you had a bag of of stuff and you also had a convex lens in there it could be good if u can't start a fire by rubbing to sticks instead you can use the convex lens to start a fire

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Find the equivalent resistance Req between terminals a and b if terminals c and d are open and again if terminals c and d are sh
adoni [48]

Answer:

351 ohm

720 ohm

Explanation:

When c and d are open:

Terminals c and d are open.. If you  redraw the circuit as below, you can see that the two resistors in the first  column are in parallel as, they are connected together at both pairs of terminals  (due to the short).

Hence, we have a pair of parallel resistors:

Req1 = (R1*R2)/ (R1 + R2) = 360*540/(360+540) = 216 ohms

Req2 = (R3*R4)/ (R3 + R4) = 180*540/(180+540) = 135 ohms

Now these two sets are  in series with another Hence,

Req = Req1 + Req2 = 216 + 135 = 351 ohms

Answer: 351 ohms

When c and d are shorted:

The current will flow through the least resistant path naturally from resistors R3 and R1 or R4.

Both of these resistor lie in a single path placing the resistors in series to one another, hence

Req = R3 + R1 = 180 + 540 = 720 ohms

Answer:720 ohms

7 0
3 years ago
Find the sum of the vectors:11 km N ,11km E
vladimir1956 [14]

The resultant vector is 11√2 km due north east.

<h3><u>Explanation:</u></h3>

The vector is a type of quantity which has both magnitude and direction. This quantities when expressed needs to specify both magnitude and direction.

We need to calculate the magnitude and direction separately.

Here firstly for the magnitude,

The magnitudes are both 11 km and they are at right angles to each other.

So, the resultant magnitude = √(11² +11²) km

=11√2 km

Now for the direction, one vector is due north and the other is due east.

So the resultant vector is due north east.

So the final vector is 11√2 km due North-East.

6 0
3 years ago
In the decomposition of water, why is twice as much hydrogen as oxygen formed?
astra-53 [7]

Answer:

I think

D : Hydrogen gas has two atom , and oxygen has one atom

7 0
2 years ago
Which use of iron is due to its chemical properties?
AfilCa [17]
Colored sparks and rusting.
3 0
2 years ago
27 degrees to kelvin, 20 dg to milligrams, and 3 to decimeters.
Gala2k [10]
K = C + 273, so 27°C = 27+273 = 300 K

1 dg = 100 mg, so 20 dg = 20×100 = 2,000 mg
7 0
3 years ago
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